{"gene":"PF3D7_1246400","run_date":"2026-09-08T14:19:06","timeline":{"discoveries":[{"year":2003,"finding":"MTIP (PF3D7_1246400) was identified as a novel 24 kDa protein that interacts with MyoA via a yeast two-hybrid screen; deletion analysis showed that specifically the 15 amino-acid C-terminal tail domain of MyoA (not the neck domain) mediates this interaction. In Plasmodium sporozoites, MTIP localizes to the inner membrane complex (IMC), clustered with MyoA, supporting a model in which MyoA is immobilized at the outer IMC membrane via its tail domain binding to MTIP.","method":"Yeast two-hybrid screen with deletion analysis; indirect immunofluorescence/localization in sporozoites","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 2 / Strong — yeast two-hybrid with deletion mapping plus direct localization, foundational study replicated in subsequent work","pmids":["12456714"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2005,"finding":"MTIP in P. falciparum merozoites localizes to the cell periphery and forms a complex with myosin A. The MTIP–MyoA tail interaction has a Kd of ~235 nM; calcium ions do not modulate this binding affinity despite a predicted EF-hand in MTIP. Antibodies to MTIP were used to immobilise the MTIP–MyoA complex, enabling measurement of actin filament velocity (3.51 µm s⁻¹). A short peptide from the MyoA tail (C-MyoA) bound MTIP and disrupted the MTIP–MyoA association in parasite lysates.","method":"Co-immunoprecipitation, in vitro actin gliding assay, fluorescence anisotropy/binding affinity measurement, peptide competition assay","journal":"Journal of molecular biology","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — multiple orthogonal biochemical methods (binding affinity, motility assay, peptide disruption, Co-IP) in single lab","pmids":["16337961"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2006,"finding":"Crystal structure of MTIP alone and in complex with the MyoA tail helix reveals that MTIP undergoes major conformational changes in its C-terminal domain upon binding the MyoA tail, creating hydrophobic pockets that accommodate key hydrophobic side chains of MyoA. Three different conformations of MTIP were observed crystallographically. The MyoA helix peptide was shown to block parasite growth.","method":"X-ray crystallography; parasite growth inhibition assay with MyoA helix peptide","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 / Moderate — crystal structure with multiple conformations and functional validation by growth inhibition, single lab","pmids":["16547135"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2007,"finding":"At neutral pH, MTIP in complex with MyoA adopts a compact conformation with both domains completely surrounding the MyoA tail helix—dramatically different from previously observed extended structures. Crystallographic and mutagenesis studies show that H810 and K813 of MyoA are key for formation of the compact MTIP:MyoA complex; only the unprotonated state of MyoA-H810 is compatible with the compact complex, and every side-chain atom of K813 contacts MTIP.","method":"X-ray crystallography; site-directed mutagenesis of MyoA residues","journal":"Journal of molecular biology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — crystal structure combined with mutagenesis establishing key contact residues, single lab","pmids":["17628590"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2008,"finding":"MTIP (PF3D7_1246400) is a substrate of P. falciparum CDPK1; CDPK1 phosphorylates MTIP in vitro, with a primary phosphorylation site at serine 47. CDPK1 localizes to the periphery of merozoites, placing it at the IMC where MTIP resides. A proportion of MTIP is phosphorylated in schizonts in vivo.","method":"In vitro kinase assay, phosphopeptide identification from parasite lysates, indirect immunofluorescence","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — in vitro kinase assay with site mapping plus detection of phosphorylation in parasite lysates, single lab with multiple methods","pmids":["18768477"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2009,"finding":"MTIP (referred to as Myosin Light Chain 1/MLC1 in that paper) was found in association with Rab11A. Rab11A-mediated vesicular trafficking driven by an MTIP–Myosin motor is proposed to be necessary for IMC maturation and delivery of new plasma membrane to daughter cells to complete cytokinesis; ablation of Rab11A function results in an incompletely formed IMC and a block at a late stage of cell division.","method":"Co-immunoprecipitation (Rab11A with MTIP); conditional expression of dominant-negative Rab11A and myosin A tail-only mutant; fluorescence microscopy","journal":"PLoS pathogens","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — single Co-IP identifying MTIP–Rab11A association, functional link inferred from Rab11A knockdown phenotype rather than direct manipulation of MTIP","pmids":["19165333"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2010,"finding":"Solution NMR characterization of the MTIP–MyoA complex identified key determinants of binding at the MTIP/MyoA interface in solution, consistent with and complementing the crystallographic data.","method":"Protein NMR (solution)","journal":"Molecular bioSystems","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — NMR structural study in solution, single lab, abstract provides limited methodological detail","pmids":["20174678"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2012,"finding":"MTIP residues Ser-107 and/or Ser-108 form an interaction hotspot with the MyoA tail as established by X-ray crystallography and NMR. The S108E phosphomimetic mutation breaks the tight clamp of MTIP around the MyoA tail; S107E has a smaller but measurable impact. These effects were confirmed by biophysical measurements and by testing recombinant MTIP S107E/S108E variants against native MyoA from P. falciparum lysates, supporting a model in which phosphorylation of MTIP at this region loosens its grip on MyoA.","method":"X-ray crystallography, NMR relaxation experiments, biophysical binding assays, phosphomimetic mutagenesis (S107E, S108E), pull-down with native parasite lysate","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — crystal structure plus NMR plus mutagenesis plus native lysate validation, multiple orthogonal methods in single lab","pmids":["22932904"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2013,"finding":"Crystal structure of the D3 (major MyoA-binding) domain of P. falciparum MTIP in complex with an anti-MTIP nanobody shows that the MyoA-binding groove in MTIP-D3 is considerably less accessible in the nanobody-bound state than when occupied by the MyoA helix, due to a shift of two helices. The nanobody binding site slightly overlaps with the MyoA binding groove.","method":"X-ray crystallography of MTIP-D3–nanobody complex","journal":"Molecular and biochemical parasitology","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — crystal structure, single lab, limited functional follow-up in abstract","pmids":["23831371"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2013,"finding":"Crystal structure of the compact P. knowlesi MTIP–MyoA complex confirms that P. knowlesi MTIP can adopt either compact or extended conformations depending on pH; above pH ~7.0 key hydrogen bonds are formed by MyoA His810 imidazole with an MTIP aspartate from the hinge and a MyoA lysine simultaneously, enabling the compact conformation.","method":"X-ray crystallography at multiple pH values","journal":"Molecular and biochemical parasitology","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — crystal structures at varied pH, single lab, structural finding only","pmids":["23831369"],"is_preprint":false,"attribution":[{"species":"Plasmodium knowlesi","strain":""}]},{"year":2017,"finding":"In P. berghei, MTIP (as part of the glideosome) co-localizes with MyoA at the parasite periphery in extracellular ookinetes, sporozoites, and merozoites. An additional essential light chain (ELC) was found in the glideosome that binds the MyoA neck region adjacent to the MTIP-binding site; both MTIP and ELC co-locate to the glideosome. Co-expression of MyoA with both MTIP and ELC enhances MyoA-dependent actin motility more than with MTIP alone.","method":"Immunofluorescence throughout P. berghei life cycle; co-expression with actin gliding assay","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct localization across life cycle plus in vitro motility assay with defined light chain composition, single lab","pmids":["28893907"],"is_preprint":false,"attribution":[{"species":"Plasmodium berghei","strain":""},{"species":"Plasmodium falciparum","strain":""}]},{"year":2017,"finding":"Reconstitution of the P. falciparum glideosome core showed that MTIP binds the MyoA heavy chain independently of ELC, whereas ELC binding to the heavy chain requires MTIP to be already bound. Neither calcium nor deletion of the MTIP N-terminal extension changed actin filament velocity. MTIP co-purified with full-length PfMyoA isolated from parasite lysates, confirming endogenous complex formation.","method":"Baculovirus/Sf9 recombinant expression and reconstitution; in vitro actin gliding assay; co-purification from parasite lysates","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — reconstitution in vitro with systematic light chain removal/addition and functional motility assay, plus native co-purification validation","pmids":["28978649"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2019,"finding":"In P. berghei motile ookinetes, MTIP is recruited to the apical end independently of the presence of MyoA. In infective sporozoites, MTIP displays a polarized distribution during gliding that is abrogated in parasites with aberrant locomotion (hsp20 mutants). In MyoA-knockout ookinetes, MTIP still localizes apically, demonstrating that MyoA is not required for MTIP's apical recruitment.","method":"Immunofluorescence microscopy of wild-type and MyoA/HSP20 knockout P. berghei motile stages","journal":"Molecular and biochemical parasitology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct localization in genetic mutants (MyoA KO, HSP20 KO) with defined subcellular phenotype, single lab","pmids":["31874192"],"is_preprint":false,"attribution":[{"species":"Plasmodium berghei","strain":""}]},{"year":2020,"finding":"Full-length PfMyoA structure in two motor-cycle states reveals the mode of recognition of MTIP by one of two degenerate IQ motifs in the MyoA lever arm. Kinetic and motility assays with PfMyoA variants demonstrate how MTIP binding contributes to the mechano-chemical properties of the motor.","method":"Cryo-EM/X-ray crystallography of full-length PfMyoA; kinetic ATPase assays; actin motility assays with MyoA variants","journal":"eLife","confidence":"High","confidence_rationale":"Tier 1 / Moderate — full-length structure plus biochemical/kinetic validation of MTIP binding mode, single lab with multiple orthogonal methods","pmids":["33046215"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2018,"finding":"In vitro pull-down and competition assays with differentially tagged recombinant proteins showed that P. falciparum MyoB can interact with MTIP in vitro, suggesting MTIP may act as the light chain of PfMyoB as well as PfMyoA.","method":"In vitro pull-down assays with recombinant proteins; competition assays with MyoA tail peptide","journal":"Parasitology research","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, in vitro pull-down only, no in vivo confirmation; direct relevance to MTIP function is speculative","pmids":["30094538"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2022,"finding":"Blocking palmitoylation of MTIP reduced its phosphorylation, and blocking phosphorylation abrogated its palmitoylation, revealing a crosstalk between these two PTMs on MTIP. As a result of this crosstalk, MTIP's interaction with myosin A was abrogated. The crosstalk between phosphorylation and palmitoylation was confirmed at a global proteome level by click chemistry, and the phenotypic effect was observed as synergistic inhibition of P. falciparum invasion in a checkerboard assay.","method":"Chemical inhibitor treatments (blocking palmitoylation and phosphorylation separately), click chemistry proteomics, co-immunoprecipitation/interaction assay, invasion checkerboard assay","journal":"Frontiers in cellular and infection microbiology","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — multiple methods (click chemistry, interaction assay, functional invasion assay) but single lab and abstract does not detail mutagenesis controls","pmids":["36250062"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]}],"current_model":"MTIP (PF3D7_1246400) is a ~24 kDa light chain of the P. falciparum glideosome that anchors MyoA to the inner membrane complex by binding the 15-amino-acid C-terminal tail helix of MyoA through large conformational changes in its C-terminal domain (compact vs. extended states), with MTIP binding the heavy chain independently of the essential light chain ELC; MTIP is phosphorylated by CDPK1 at Ser-47, and additional phosphorylation at Ser-107/Ser-108 loosens its grip on the MyoA tail, while a crosstalk between palmitoylation and phosphorylation of MTIP further regulates its interaction with MyoA and parasite invasion."},"narrative":{"mechanistic_narrative":"MTIP (PF3D7_1246400) is a ~24 kDa myosin light chain that anchors the class XIV motor MyoA to the inner membrane complex (IMC), forming the core of the Plasmodium glideosome that drives gliding motility and host-cell invasion [PMID:12456714, PMID:16337961]. It binds the 15-amino-acid C-terminal tail helix of MyoA with sub-micromolar affinity, and antibody-immobilized MTIP–MyoA complexes power actin filament gliding in vitro, establishing MTIP as the tail-anchoring component of a functional motor [PMID:12456714, PMID:16337961]. Structural work resolved this interaction in atomic detail: MTIP undergoes large conformational changes in its C-terminal domain upon binding the MyoA tail, collapsing from extended into a pH-dependent compact state in which both domains wrap the helix, with MyoA His810 and Lys813 as decisive contacts [PMID:16547135, PMID:17628590]; full-length PfMyoA structures further show MTIP is recognized by a degenerate IQ motif of the MyoA lever arm and contributes to the motor's mechano-chemical output [PMID:33046215]. Within the reconstituted glideosome, MTIP binds the MyoA heavy chain independently, and is a prerequisite for subsequent binding of the essential light chain (ELC) to the adjacent neck region, the two light chains together enhancing motility beyond MTIP alone [PMID:28978649, PMID:28893907]. MTIP function is regulated post-translationally: CDPK1 phosphorylates it at Ser-47 [PMID:18768477], phosphomimetic substitution at Ser-107/Ser-108 breaks the tight clamp around the MyoA tail [PMID:22932904], and a crosstalk between palmitoylation and phosphorylation modulates the MTIP–MyoA interaction and parasite invasion [PMID:36250062]. In P. berghei motile stages MTIP is recruited apically independently of MyoA, indicating its IMC targeting does not require its motor partner [PMID:31874192].","teleology":[{"year":2003,"claim":"Establishing what tethers the invasion motor to the membrane, MTIP was defined as the MyoA-binding, IMC-localized protein that immobilizes the motor via the MyoA tail.","evidence":"Yeast two-hybrid with deletion mapping and immunofluorescence localization in sporozoites","pmids":["12456714"],"confidence":"High","gaps":["Binding affinity and stoichiometry not yet quantified","Functional consequence of the tether for motility not shown"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2005,"claim":"To show the tether supports a working motor, the MTIP–MyoA complex was quantified and its motor activity measured, and a competing peptide was shown to disrupt the complex.","evidence":"Co-IP, fluorescence anisotropy binding, in vitro actin gliding assay, and peptide competition in parasite lysate","pmids":["16337961"],"confidence":"High","gaps":["Predicted EF-hand role unresolved beyond calcium not modulating binding","Structural basis of binding not yet defined"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2006,"claim":"To explain how MTIP grips the MyoA tail, crystallography revealed large C-terminal-domain conformational changes forming hydrophobic pockets, and a MyoA helix peptide blocked parasite growth, validating the interface as a target.","evidence":"X-ray crystallography of MTIP and MTIP–MyoA tail complex plus growth inhibition assay","pmids":["16547135"],"confidence":"High","gaps":["Physiological trigger selecting among the three observed conformations unknown"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2007,"claim":"To resolve which conformation operates in vivo, a pH-dependent compact complex enveloping the MyoA helix was defined, pinpointing MyoA His810 and Lys813 as governing contacts.","evidence":"X-ray crystallography with site-directed mutagenesis of MyoA residues","pmids":["17628590"],"confidence":"High","gaps":["Whether pH-dependent switching occurs during invasion in the cell not demonstrated"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2008,"claim":"To identify regulation of the tether, MTIP was shown to be a CDPK1 substrate phosphorylated at Ser-47, linking a peripheral kinase to the glideosome.","evidence":"In vitro kinase assay with phosphosite mapping, phosphopeptide detection from lysates, immunofluorescence","pmids":["18768477"],"confidence":"High","gaps":["Functional consequence of Ser-47 phosphorylation on MyoA binding not established","Stoichiometry of in vivo phosphorylation unclear"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2009,"claim":"Extending MTIP beyond the assembled motor, its association with Rab11A implicated an MTIP–myosin motor in vesicular trafficking for IMC maturation and cytokinesis.","evidence":"Co-IP of Rab11A with MTIP plus dominant-negative Rab11A and MyoA-tail mutant expression with microscopy","pmids":["19165333"],"confidence":"Medium","gaps":["Functional link inferred from Rab11A manipulation rather than direct MTIP perturbation","Direct MTIP–Rab11A binding not mapped"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2010,"claim":"To confirm the crystallographic interface holds in solution, NMR identified the key binding determinants at the MTIP/MyoA interface.","evidence":"Solution protein NMR of the MTIP–MyoA complex","pmids":["20174678"],"confidence":"Medium","gaps":["Dynamics of the conformational switch not quantified in this study"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2012,"claim":"To connect phosphorylation to motor regulation, Ser-107/Ser-108 were defined as a binding hotspot whose phosphomimetic substitution loosens the MTIP clamp on the MyoA tail.","evidence":"X-ray crystallography, NMR relaxation, biophysical binding assays, and S107E/S108E phosphomimetics tested against native MyoA in lysate","pmids":["22932904"],"confidence":"High","gaps":["Kinase responsible for Ser-107/Ser-108 phosphorylation not identified","In vivo timing of this regulation during invasion unknown"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2013,"claim":"To assess the MyoA-binding groove as a drug/nanobody target, the MTIP-D3–nanobody structure showed nanobody binding occludes the groove via a two-helix shift.","evidence":"X-ray crystallography of the MTIP-D3–nanobody complex","pmids":["23831371"],"confidence":"Medium","gaps":["Functional inhibition of the motor by the nanobody not demonstrated in parasites"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2013,"claim":"To generalize the pH-switch mechanism across species, the compact P. knowlesi MTIP–MyoA complex confirmed pH-dependent compact/extended states via His810-anchored hydrogen bonds.","evidence":"X-ray crystallography at multiple pH values in P. knowlesi","pmids":["23831369"],"confidence":"Medium","gaps":["Physiological pH range experienced by the complex in vivo not defined"],"attribution":[{"species":"Plasmodium knowlesi","strain":""}]},{"year":2017,"claim":"To define the full light-chain composition of the glideosome, ELC was found to bind the MyoA neck adjacent to MTIP, and co-expression with both light chains enhanced motility beyond MTIP alone.","evidence":"Immunofluorescence across the P. berghei life cycle plus co-expression actin gliding assay","pmids":["28893907"],"confidence":"Medium","gaps":["Regulatory interplay between MTIP and ELC during invasion not resolved"],"attribution":[{"species":"Plasmodium berghei","strain":""},{"species":"Plasmodium falciparum","strain":""}]},{"year":2017,"claim":"To order light-chain assembly, reconstitution showed MTIP binds the MyoA heavy chain independently while ELC binding requires MTIP to be bound first.","evidence":"Recombinant reconstitution with systematic light-chain removal, actin gliding assay, and native co-purification","pmids":["28978649"],"confidence":"High","gaps":["Structural basis for MTIP-dependent ELC recruitment not shown","Role of the MTIP N-terminal extension unresolved beyond no effect on velocity"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2018,"claim":"Probing whether MTIP serves motors beyond MyoA, in vitro assays showed it can also interact with MyoB, hinting at a shared light-chain role.","evidence":"In vitro pull-down and MyoA-tail competition assays with recombinant proteins","pmids":["30094538"],"confidence":"Low","gaps":["In vitro pull-down only, not confirmed in vivo","Physiological relevance of MTIP–MyoB association unknown"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2019,"claim":"To test whether MTIP targeting depends on its motor partner, P. berghei genetics showed MTIP is recruited apically independently of MyoA and adopts a polarized distribution during gliding.","evidence":"Immunofluorescence of MyoA-knockout and HSP20-mutant P. berghei motile stages","pmids":["31874192"],"confidence":"Medium","gaps":["Molecular determinant driving MTIP's MyoA-independent apical recruitment unknown"],"attribution":[{"species":"Plasmodium berghei","strain":""}]},{"year":2020,"claim":"To situate MTIP within the working motor, the full-length PfMyoA structure revealed MTIP recognition by a degenerate IQ motif of the lever arm and its contribution to motor mechano-chemistry.","evidence":"Full-length PfMyoA structure with kinetic ATPase and motility assays of MyoA variants","pmids":["33046215"],"confidence":"High","gaps":["How phosphorylation-driven MTIP conformational changes alter the working stroke not directly measured"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2022,"claim":"To connect two PTMs to invasion, palmitoylation and phosphorylation of MTIP were shown to be mutually dependent, and disrupting this crosstalk abrogated MTIP–MyoA binding and synergistically inhibited invasion.","evidence":"Chemical inhibitor treatments, click-chemistry proteomics, interaction assay, and invasion checkerboard assay","pmids":["36250062"],"confidence":"Medium","gaps":["Specific palmitoylation site(s) on MTIP not mapped","Enzymes mediating MTIP palmitoylation not identified","Effects inferred from inhibitors rather than site-directed mutagenesis"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":null,"claim":"How the multiple regulatory inputs on MTIP (Ser-47 by CDPK1, Ser-107/Ser-108, and palmitoylation crosstalk) are temporally coordinated to control motor engagement and disengagement during a single invasion cycle remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unified model linking each PTM to a defined step of gliding/invasion","In vivo consequences of phosphosite mutations in living parasites not established"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]}],"mechanism_profile":{"molecular_activity":[],"localization":[],"pathway":[],"complexes":["Glideosome (MyoA–MTIP–ELC motor complex)"],"partners":["MYOA (MYOSIN A HEAVY CHAIN; C-TERMINAL TAIL HELIX, HIS810/LYS813)","ELC (ESSENTIAL LIGHT CHAIN; BINDS MYOA NECK, REQUIRES MTIP BOUND FIRST)","CDPK1 (PHOSPHORYLATES MTIP AT SER-47)","RAB11A (CO-IMMUNOPRECIPITATION ASSOCIATION)","MYOB (IN VITRO INTERACTION ONLY)"],"other_free_text":["Undergoes pH-dependent compact/extended conformational switch of its C-terminal domain upon MyoA-tail binding","Phosphomimetic S108E (and to a lesser extent S107E) loosens the clamp on the MyoA tail","Palmitoylation and phosphorylation of MTIP are mutually dependent, and their crosstalk regulates MyoA binding and invasion","MyoA-binding groove targetable by an anti-MTIP nanobody and by a competing MyoA helix peptide (growth inhibitory)","In P. berghei, apical recruitment of MTIP is independent of MyoA"]}},"prefetch_data":{},"corpus_meta":[{"pmid":"12456714","id":"PMC_12456714","title":"Myosin A tail domain interacting protein (MTIP) localizes to the inner membrane complex of Plasmodium sporozoites.","date":"2003","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/12456714","citation_count":166,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["MTIP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"18768477","id":"PMC_18768477","title":"The motor complex of Plasmodium falciparum: phosphorylation by a calcium-dependent protein kinase.","date":"2008","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/18768477","citation_count":147,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["MTIP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"19165333","id":"PMC_19165333","title":"Rab11A-controlled assembly of the inner membrane complex is required for completion of apicomplexan cytokinesis.","date":"2009","source":"PLoS pathogens","url":"https://pubmed.ncbi.nlm.nih.gov/19165333","citation_count":95,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["MTIP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"16337961","id":"PMC_16337961","title":"The MTIP-myosin A complex in blood stage malaria parasites.","date":"2005","source":"Journal of molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/16337961","citation_count":70,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["MTIP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"16547135","id":"PMC_16547135","title":"Structure of the MTIP-MyoA complex, a key component of the malaria parasite invasion motor.","date":"2006","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/16547135","citation_count":60,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["MTIP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"22479457","id":"PMC_22479457","title":"Subcellular location, phosphorylation and assembly into the motor complex of GAP45 during Plasmodium falciparum schizont development.","date":"2012","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/22479457","citation_count":55,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["MTIP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"21239623","id":"PMC_21239623","title":"Tracking Glideosome-associated protein 50 reveals the development and organization of the inner membrane complex of Plasmodium falciparum.","date":"2011","source":"Eukaryotic cell","url":"https://pubmed.ncbi.nlm.nih.gov/21239623","citation_count":48,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["MTIP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"17628590","id":"PMC_17628590","title":"The closed MTIP-myosin A-tail complex from the malaria parasite invasion machinery.","date":"2007","source":"Journal of molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/17628590","citation_count":46,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["MTIP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"20426475","id":"PMC_20426475","title":"Structure-based design of novel small-molecule inhibitors of Plasmodium falciparum.","date":"2010","source":"Journal of chemical information and modeling","url":"https://pubmed.ncbi.nlm.nih.gov/20426475","citation_count":44,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["MTIP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"25084543","id":"PMC_25084543","title":"Crystal structures of stapled and hydrogen bond surrogate peptides targeting a fully buried protein-helix interaction.","date":"2014","source":"ACS chemical 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bioSystems","url":"https://pubmed.ncbi.nlm.nih.gov/20174678","citation_count":27,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["MTIP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"25802338","id":"PMC_25802338","title":"The Plasmodium Class XIV Myosin, MyoB, Has a Distinct Subcellular Location in Invasive and Motile Stages of the Malaria Parasite and an Unusual Light Chain.","date":"2015","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/25802338","citation_count":27,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["MTIP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"28978649","id":"PMC_28978649","title":"Reconstitution of the core of the malaria parasite glideosome with recombinant Plasmodium class XIV myosin A and Plasmodium actin.","date":"2017","source":"The Journal of 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Society","url":"https://pubmed.ncbi.nlm.nih.gov/40316890","citation_count":0,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["MTIP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":15321,"output_tokens":4677,"usd":0.058059,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":10977,"output_tokens":5692,"usd":0.098592,"stage2_stop_reason":"end_turn"},"total_usd":0.156651,"stage1_batch_id":"msgbatch_011BPjN2BL33F8cJXD1r7V7T","stage2_batch_id":"msgbatch_01Qwg6vP7qxkpL6Gsc7tajsb","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2003,\n      \"finding\": \"MTIP (PF3D7_1246400) was identified as a novel 24 kDa protein that interacts with MyoA via a yeast two-hybrid screen; deletion analysis showed that specifically the 15 amino-acid C-terminal tail domain of MyoA (not the neck domain) mediates this interaction. In Plasmodium sporozoites, MTIP localizes to the inner membrane complex (IMC), clustered with MyoA, supporting a model in which MyoA is immobilized at the outer IMC membrane via its tail domain binding to MTIP.\",\n      \"method\": \"Yeast two-hybrid screen with deletion analysis; indirect immunofluorescence/localization in sporozoites\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — yeast two-hybrid with deletion mapping plus direct localization, foundational study replicated in subsequent work\",\n      \"pmids\": [\"12456714\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}\n      ]\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"MTIP in P. falciparum merozoites localizes to the cell periphery and forms a complex with myosin A. The MTIP–MyoA tail interaction has a Kd of ~235 nM; calcium ions do not modulate this binding affinity despite a predicted EF-hand in MTIP. Antibodies to MTIP were used to immobilise the MTIP–MyoA complex, enabling measurement of actin filament velocity (3.51 µm s⁻¹). A short peptide from the MyoA tail (C-MyoA) bound MTIP and disrupted the MTIP–MyoA association in parasite lysates.\",\n      \"method\": \"Co-immunoprecipitation, in vitro actin gliding assay, fluorescence anisotropy/binding affinity measurement, peptide competition assay\",\n      \"journal\": \"Journal of molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — multiple orthogonal biochemical methods (binding affinity, motility assay, peptide disruption, Co-IP) in single lab\",\n      \"pmids\": [\"16337961\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}\n      ]\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Crystal structure of MTIP alone and in complex with the MyoA tail helix reveals that MTIP undergoes major conformational changes in its C-terminal domain upon binding the MyoA tail, creating hydrophobic pockets that accommodate key hydrophobic side chains of MyoA. Three different conformations of MTIP were observed crystallographically. The MyoA helix peptide was shown to block parasite growth.\",\n      \"method\": \"X-ray crystallography; parasite growth inhibition assay with MyoA helix peptide\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — crystal structure with multiple conformations and functional validation by growth inhibition, single lab\",\n      \"pmids\": [\"16547135\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}\n      ]\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"At neutral pH, MTIP in complex with MyoA adopts a compact conformation with both domains completely surrounding the MyoA tail helix—dramatically different from previously observed extended structures. Crystallographic and mutagenesis studies show that H810 and K813 of MyoA are key for formation of the compact MTIP:MyoA complex; only the unprotonated state of MyoA-H810 is compatible with the compact complex, and every side-chain atom of K813 contacts MTIP.\",\n      \"method\": \"X-ray crystallography; site-directed mutagenesis of MyoA residues\",\n      \"journal\": \"Journal of molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — crystal structure combined with mutagenesis establishing key contact residues, single lab\",\n      \"pmids\": [\"17628590\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}\n      ]\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"MTIP (PF3D7_1246400) is a substrate of P. falciparum CDPK1; CDPK1 phosphorylates MTIP in vitro, with a primary phosphorylation site at serine 47. CDPK1 localizes to the periphery of merozoites, placing it at the IMC where MTIP resides. A proportion of MTIP is phosphorylated in schizonts in vivo.\",\n      \"method\": \"In vitro kinase assay, phosphopeptide identification from parasite lysates, indirect immunofluorescence\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — in vitro kinase assay with site mapping plus detection of phosphorylation in parasite lysates, single lab with multiple methods\",\n      \"pmids\": [\"18768477\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}\n      ]\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"MTIP (referred to as Myosin Light Chain 1/MLC1 in that paper) was found in association with Rab11A. Rab11A-mediated vesicular trafficking driven by an MTIP–Myosin motor is proposed to be necessary for IMC maturation and delivery of new plasma membrane to daughter cells to complete cytokinesis; ablation of Rab11A function results in an incompletely formed IMC and a block at a late stage of cell division.\",\n      \"method\": \"Co-immunoprecipitation (Rab11A with MTIP); conditional expression of dominant-negative Rab11A and myosin A tail-only mutant; fluorescence microscopy\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — single Co-IP identifying MTIP–Rab11A association, functional link inferred from Rab11A knockdown phenotype rather than direct manipulation of MTIP\",\n      \"pmids\": [\"19165333\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}\n      ]\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Solution NMR characterization of the MTIP–MyoA complex identified key determinants of binding at the MTIP/MyoA interface in solution, consistent with and complementing the crystallographic data.\",\n      \"method\": \"Protein NMR (solution)\",\n      \"journal\": \"Molecular bioSystems\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — NMR structural study in solution, single lab, abstract provides limited methodological detail\",\n      \"pmids\": [\"20174678\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}\n      ]\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"MTIP residues Ser-107 and/or Ser-108 form an interaction hotspot with the MyoA tail as established by X-ray crystallography and NMR. The S108E phosphomimetic mutation breaks the tight clamp of MTIP around the MyoA tail; S107E has a smaller but measurable impact. These effects were confirmed by biophysical measurements and by testing recombinant MTIP S107E/S108E variants against native MyoA from P. falciparum lysates, supporting a model in which phosphorylation of MTIP at this region loosens its grip on MyoA.\",\n      \"method\": \"X-ray crystallography, NMR relaxation experiments, biophysical binding assays, phosphomimetic mutagenesis (S107E, S108E), pull-down with native parasite lysate\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — crystal structure plus NMR plus mutagenesis plus native lysate validation, multiple orthogonal methods in single lab\",\n      \"pmids\": [\"22932904\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}\n      ]\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Crystal structure of the D3 (major MyoA-binding) domain of P. falciparum MTIP in complex with an anti-MTIP nanobody shows that the MyoA-binding groove in MTIP-D3 is considerably less accessible in the nanobody-bound state than when occupied by the MyoA helix, due to a shift of two helices. The nanobody binding site slightly overlaps with the MyoA binding groove.\",\n      \"method\": \"X-ray crystallography of MTIP-D3–nanobody complex\",\n      \"journal\": \"Molecular and biochemical parasitology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — crystal structure, single lab, limited functional follow-up in abstract\",\n      \"pmids\": [\"23831371\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}\n      ]\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Crystal structure of the compact P. knowlesi MTIP–MyoA complex confirms that P. knowlesi MTIP can adopt either compact or extended conformations depending on pH; above pH ~7.0 key hydrogen bonds are formed by MyoA His810 imidazole with an MTIP aspartate from the hinge and a MyoA lysine simultaneously, enabling the compact conformation.\",\n      \"method\": \"X-ray crystallography at multiple pH values\",\n      \"journal\": \"Molecular and biochemical parasitology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — crystal structures at varied pH, single lab, structural finding only\",\n      \"pmids\": [\"23831369\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Plasmodium knowlesi\", \"strain\": \"\"}\n      ]\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"In P. berghei, MTIP (as part of the glideosome) co-localizes with MyoA at the parasite periphery in extracellular ookinetes, sporozoites, and merozoites. An additional essential light chain (ELC) was found in the glideosome that binds the MyoA neck region adjacent to the MTIP-binding site; both MTIP and ELC co-locate to the glideosome. Co-expression of MyoA with both MTIP and ELC enhances MyoA-dependent actin motility more than with MTIP alone.\",\n      \"method\": \"Immunofluorescence throughout P. berghei life cycle; co-expression with actin gliding assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct localization across life cycle plus in vitro motility assay with defined light chain composition, single lab\",\n      \"pmids\": [\"28893907\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Plasmodium berghei\", \"strain\": \"\"},\n        {\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}\n      ]\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Reconstitution of the P. falciparum glideosome core showed that MTIP binds the MyoA heavy chain independently of ELC, whereas ELC binding to the heavy chain requires MTIP to be already bound. Neither calcium nor deletion of the MTIP N-terminal extension changed actin filament velocity. MTIP co-purified with full-length PfMyoA isolated from parasite lysates, confirming endogenous complex formation.\",\n      \"method\": \"Baculovirus/Sf9 recombinant expression and reconstitution; in vitro actin gliding assay; co-purification from parasite lysates\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — reconstitution in vitro with systematic light chain removal/addition and functional motility assay, plus native co-purification validation\",\n      \"pmids\": [\"28978649\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}\n      ]\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"In P. berghei motile ookinetes, MTIP is recruited to the apical end independently of the presence of MyoA. In infective sporozoites, MTIP displays a polarized distribution during gliding that is abrogated in parasites with aberrant locomotion (hsp20 mutants). In MyoA-knockout ookinetes, MTIP still localizes apically, demonstrating that MyoA is not required for MTIP's apical recruitment.\",\n      \"method\": \"Immunofluorescence microscopy of wild-type and MyoA/HSP20 knockout P. berghei motile stages\",\n      \"journal\": \"Molecular and biochemical parasitology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct localization in genetic mutants (MyoA KO, HSP20 KO) with defined subcellular phenotype, single lab\",\n      \"pmids\": [\"31874192\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Plasmodium berghei\", \"strain\": \"\"}\n      ]\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Full-length PfMyoA structure in two motor-cycle states reveals the mode of recognition of MTIP by one of two degenerate IQ motifs in the MyoA lever arm. Kinetic and motility assays with PfMyoA variants demonstrate how MTIP binding contributes to the mechano-chemical properties of the motor.\",\n      \"method\": \"Cryo-EM/X-ray crystallography of full-length PfMyoA; kinetic ATPase assays; actin motility assays with MyoA variants\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — full-length structure plus biochemical/kinetic validation of MTIP binding mode, single lab with multiple orthogonal methods\",\n      \"pmids\": [\"33046215\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}\n      ]\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"In vitro pull-down and competition assays with differentially tagged recombinant proteins showed that P. falciparum MyoB can interact with MTIP in vitro, suggesting MTIP may act as the light chain of PfMyoB as well as PfMyoA.\",\n      \"method\": \"In vitro pull-down assays with recombinant proteins; competition assays with MyoA tail peptide\",\n      \"journal\": \"Parasitology research\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, in vitro pull-down only, no in vivo confirmation; direct relevance to MTIP function is speculative\",\n      \"pmids\": [\"30094538\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}\n      ]\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Blocking palmitoylation of MTIP reduced its phosphorylation, and blocking phosphorylation abrogated its palmitoylation, revealing a crosstalk between these two PTMs on MTIP. As a result of this crosstalk, MTIP's interaction with myosin A was abrogated. The crosstalk between phosphorylation and palmitoylation was confirmed at a global proteome level by click chemistry, and the phenotypic effect was observed as synergistic inhibition of P. falciparum invasion in a checkerboard assay.\",\n      \"method\": \"Chemical inhibitor treatments (blocking palmitoylation and phosphorylation separately), click chemistry proteomics, co-immunoprecipitation/interaction assay, invasion checkerboard assay\",\n      \"journal\": \"Frontiers in cellular and infection microbiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — multiple methods (click chemistry, interaction assay, functional invasion assay) but single lab and abstract does not detail mutagenesis controls\",\n      \"pmids\": [\"36250062\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}\n      ]\n    }\n  ],\n  \"current_model\": \"MTIP (PF3D7_1246400) is a ~24 kDa light chain of the P. falciparum glideosome that anchors MyoA to the inner membrane complex by binding the 15-amino-acid C-terminal tail helix of MyoA through large conformational changes in its C-terminal domain (compact vs. extended states), with MTIP binding the heavy chain independently of the essential light chain ELC; MTIP is phosphorylated by CDPK1 at Ser-47, and additional phosphorylation at Ser-107/Ser-108 loosens its grip on the MyoA tail, while a crosstalk between palmitoylation and phosphorylation of MTIP further regulates its interaction with MyoA and parasite invasion.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"MTIP (PF3D7_1246400) is a ~24 kDa myosin light chain that anchors the class XIV motor MyoA to the inner membrane complex (IMC), forming the core of the Plasmodium glideosome that drives gliding motility and host-cell invasion [#0, #1]. It binds the 15-amino-acid C-terminal tail helix of MyoA with sub-micromolar affinity, and antibody-immobilized MTIP\\u2013MyoA complexes power actin filament gliding in vitro, establishing MTIP as the tail-anchoring component of a functional motor [#0, #1]. Structural work resolved this interaction in atomic detail: MTIP undergoes large conformational changes in its C-terminal domain upon binding the MyoA tail, collapsing from extended into a pH-dependent compact state in which both domains wrap the helix, with MyoA His810 and Lys813 as decisive contacts [#2, #3]; full-length PfMyoA structures further show MTIP is recognized by a degenerate IQ motif of the MyoA lever arm and contributes to the motor's mechano-chemical output [#13]. Within the reconstituted glideosome, MTIP binds the MyoA heavy chain independently, and is a prerequisite for subsequent binding of the essential light chain (ELC) to the adjacent neck region, the two light chains together enhancing motility beyond MTIP alone [#11, #10]. MTIP function is regulated post-translationally: CDPK1 phosphorylates it at Ser-47 [#4], phosphomimetic substitution at Ser-107/Ser-108 breaks the tight clamp around the MyoA tail [#7], and a crosstalk between palmitoylation and phosphorylation modulates the MTIP\\u2013MyoA interaction and parasite invasion [#15]. In P. berghei motile stages MTIP is recruited apically independently of MyoA, indicating its IMC targeting does not require its motor partner [#12].\",\n  \"teleology\": [\n    {\n      \"year\": 2003,\n      \"claim\": \"Establishing what tethers the invasion motor to the membrane, MTIP was defined as the MyoA-binding, IMC-localized protein that immobilizes the motor via the MyoA tail.\",\n      \"evidence\": \"Yeast two-hybrid with deletion mapping and immunofluorescence localization in sporozoites\",\n      \"pmids\": [\"12456714\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Binding affinity and stoichiometry not yet quantified\", \"Functional consequence of the tether for motility not shown\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"To show the tether supports a working motor, the MTIP\\u2013MyoA complex was quantified and its motor activity measured, and a competing peptide was shown to disrupt the complex.\",\n      \"evidence\": \"Co-IP, fluorescence anisotropy binding, in vitro actin gliding assay, and peptide competition in parasite lysate\",\n      \"pmids\": [\"16337961\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Predicted EF-hand role unresolved beyond calcium not modulating binding\", \"Structural basis of binding not yet defined\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"To explain how MTIP grips the MyoA tail, crystallography revealed large C-terminal-domain conformational changes forming hydrophobic pockets, and a MyoA helix peptide blocked parasite growth, validating the interface as a target.\",\n      \"evidence\": \"X-ray crystallography of MTIP and MTIP\\u2013MyoA tail complex plus growth inhibition assay\",\n      \"pmids\": [\"16547135\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Physiological trigger selecting among the three observed conformations unknown\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"To resolve which conformation operates in vivo, a pH-dependent compact complex enveloping the MyoA helix was defined, pinpointing MyoA His810 and Lys813 as governing contacts.\",\n      \"evidence\": \"X-ray crystallography with site-directed mutagenesis of MyoA residues\",\n      \"pmids\": [\"17628590\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Whether pH-dependent switching occurs during invasion in the cell not demonstrated\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"To identify regulation of the tether, MTIP was shown to be a CDPK1 substrate phosphorylated at Ser-47, linking a peripheral kinase to the glideosome.\",\n      \"evidence\": \"In vitro kinase assay with phosphosite mapping, phosphopeptide detection from lysates, immunofluorescence\",\n      \"pmids\": [\"18768477\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Functional consequence of Ser-47 phosphorylation on MyoA binding not established\", \"Stoichiometry of in vivo phosphorylation unclear\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Extending MTIP beyond the assembled motor, its association with Rab11A implicated an MTIP\\u2013myosin motor in vesicular trafficking for IMC maturation and cytokinesis.\",\n      \"evidence\": \"Co-IP of Rab11A with MTIP plus dominant-negative Rab11A and MyoA-tail mutant expression with microscopy\",\n      \"pmids\": [\"19165333\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Functional link inferred from Rab11A manipulation rather than direct MTIP perturbation\", \"Direct MTIP\\u2013Rab11A binding not mapped\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"To confirm the crystallographic interface holds in solution, NMR identified the key binding determinants at the MTIP/MyoA interface.\",\n      \"evidence\": \"Solution protein NMR of the MTIP\\u2013MyoA complex\",\n      \"pmids\": [\"20174678\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Dynamics of the conformational switch not quantified in this study\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"To connect phosphorylation to motor regulation, Ser-107/Ser-108 were defined as a binding hotspot whose phosphomimetic substitution loosens the MTIP clamp on the MyoA tail.\",\n      \"evidence\": \"X-ray crystallography, NMR relaxation, biophysical binding assays, and S107E/S108E phosphomimetics tested against native MyoA in lysate\",\n      \"pmids\": [\"22932904\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Kinase responsible for Ser-107/Ser-108 phosphorylation not identified\", \"In vivo timing of this regulation during invasion unknown\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"To assess the MyoA-binding groove as a drug/nanobody target, the MTIP-D3\\u2013nanobody structure showed nanobody binding occludes the groove via a two-helix shift.\",\n      \"evidence\": \"X-ray crystallography of the MTIP-D3\\u2013nanobody complex\",\n      \"pmids\": [\"23831371\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Functional inhibition of the motor by the nanobody not demonstrated in parasites\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"To generalize the pH-switch mechanism across species, the compact P. knowlesi MTIP\\u2013MyoA complex confirmed pH-dependent compact/extended states via His810-anchored hydrogen bonds.\",\n      \"evidence\": \"X-ray crystallography at multiple pH values in P. knowlesi\",\n      \"pmids\": [\"23831369\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Physiological pH range experienced by the complex in vivo not defined\"],\n      \"attribution\": [{\"species\": \"Plasmodium knowlesi\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"To define the full light-chain composition of the glideosome, ELC was found to bind the MyoA neck adjacent to MTIP, and co-expression with both light chains enhanced motility beyond MTIP alone.\",\n      \"evidence\": \"Immunofluorescence across the P. berghei life cycle plus co-expression actin gliding assay\",\n      \"pmids\": [\"28893907\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Regulatory interplay between MTIP and ELC during invasion not resolved\"],\n      \"attribution\": [{\"species\": \"Plasmodium berghei\", \"strain\": \"\"}, {\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"To order light-chain assembly, reconstitution showed MTIP binds the MyoA heavy chain independently while ELC binding requires MTIP to be bound first.\",\n      \"evidence\": \"Recombinant reconstitution with systematic light-chain removal, actin gliding assay, and native co-purification\",\n      \"pmids\": [\"28978649\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Structural basis for MTIP-dependent ELC recruitment not shown\", \"Role of the MTIP N-terminal extension unresolved beyond no effect on velocity\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Probing whether MTIP serves motors beyond MyoA, in vitro assays showed it can also interact with MyoB, hinting at a shared light-chain role.\",\n      \"evidence\": \"In vitro pull-down and MyoA-tail competition assays with recombinant proteins\",\n      \"pmids\": [\"30094538\"],\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"In vitro pull-down only, not confirmed in vivo\", \"Physiological relevance of MTIP\\u2013MyoB association unknown\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"To test whether MTIP targeting depends on its motor partner, P. berghei genetics showed MTIP is recruited apically independently of MyoA and adopts a polarized distribution during gliding.\",\n      \"evidence\": \"Immunofluorescence of MyoA-knockout and HSP20-mutant P. berghei motile stages\",\n      \"pmids\": [\"31874192\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Molecular determinant driving MTIP's MyoA-independent apical recruitment unknown\"],\n      \"attribution\": [{\"species\": \"Plasmodium berghei\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"To situate MTIP within the working motor, the full-length PfMyoA structure revealed MTIP recognition by a degenerate IQ motif of the lever arm and its contribution to motor mechano-chemistry.\",\n      \"evidence\": \"Full-length PfMyoA structure with kinetic ATPase and motility assays of MyoA variants\",\n      \"pmids\": [\"33046215\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"How phosphorylation-driven MTIP conformational changes alter the working stroke not directly measured\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"To connect two PTMs to invasion, palmitoylation and phosphorylation of MTIP were shown to be mutually dependent, and disrupting this crosstalk abrogated MTIP\\u2013MyoA binding and synergistically inhibited invasion.\",\n      \"evidence\": \"Chemical inhibitor treatments, click-chemistry proteomics, interaction assay, and invasion checkerboard assay\",\n      \"pmids\": [\"36250062\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Specific palmitoylation site(s) on MTIP not mapped\", \"Enzymes mediating MTIP palmitoylation not identified\", \"Effects inferred from inhibitors rather than site-directed mutagenesis\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How the multiple regulatory inputs on MTIP (Ser-47 by CDPK1, Ser-107/Ser-108, and palmitoylation crosstalk) are temporally coordinated to control motor engagement and disengagement during a single invasion cycle remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"No unified model linking each PTM to a defined step of gliding/invasion\", \"In vivo consequences of phosphosite mutations in living parasites not established\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0003774\", \"supporting_discovery_ids\": [0, 1, 11, 13]},\n      {\"term_id\": \"GO:0032403\", \"supporting_discovery_ids\": [0, 1, 2, 3, 11]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0020039\", \"supporting_discovery_ids\": [0, 10]},\n      {\"term_id\": \"GO:0071944\", \"supporting_discovery_ids\": [1, 10]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0071693\", \"supporting_discovery_ids\": [0, 1, 11, 13]},\n      {\"term_id\": \"GO:0044409\", \"supporting_discovery_ids\": [2, 15]}\n    ],\n    \"complexes\": [\n      \"Glideosome (MyoA\\u2013MTIP\\u2013ELC motor complex)\"\n    ],\n    \"partners\": [\n      \"MyoA (myosin A heavy chain; C-terminal tail helix, His810/Lys813)\",\n      \"ELC (essential light chain; binds MyoA neck, requires MTIP bound first)\",\n      \"CDPK1 (phosphorylates MTIP at Ser-47)\",\n      \"Rab11A (co-immunoprecipitation association)\",\n      \"MyoB (in vitro interaction only)\"\n    ],\n    \"other_free_text\": [\n      \"Undergoes pH-dependent compact/extended conformational switch of its C-terminal domain upon MyoA-tail binding\",\n      \"Phosphomimetic S108E (and to a lesser extent S107E) loosens the clamp on the MyoA tail\",\n      \"Palmitoylation and phosphorylation of MTIP are mutually dependent, and their crosstalk regulates MyoA binding and invasion\",\n      \"MyoA-binding groove targetable by an anti-MTIP nanobody and by a competing MyoA helix peptide (growth inhibitory)\",\n      \"In P. berghei, apical recruitment of MTIP is independent of MyoA\"\n    ]\n  }\n}","audit_flag":null,"strains":[{"strain":"Pf3D7","gene_id":"PF3D7_1246400","name":null,"product":"myosin A-tail interacting protein","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PbANKA","gene_id":"PBANKA_1459500","name":null,"product":"myosin A-tail interacting protein","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PkH","gene_id":"PKNH_1466100","name":null,"product":"myosin A-tail interacting protein","uniprot_acc":null,"chromosome":null,"start_pos":null}],"gene_symbol":"MTIP","evaluation":null}