{"gene":"PF3D7_1434200","run_date":"2026-09-08T14:19:07","timeline":{"discoveries":[{"year":1987,"finding":"CAM (calmodulin) was detected in free P. falciparum parasites by radioimmunoassay, with levels proportional to parasite maturity. Immunoelectron microscopy localized CAM diffusely in the cytoplasm of mature parasites and specifically at the apical end of merozoites within the rhoptry ductule, suggesting a role in the calcium requirement for erythrocyte invasion.","method":"Radioimmunoassay, immunoelectron microscopy","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — two orthogonal methods (RIA and IEM) from a single lab establishing localization with functional inference, but no direct loss-of-function mechanistic confirmation","pmids":["3313391"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":1987,"finding":"CAM (calmodulin) antagonists (W7, trifluoperazine, R24571) inhibited erythrocyte invasion by merozoites and schizont maturation in P. falciparum; CAM was localized by immunoelectron microscopy at the apical end of free and intraerythrocytic merozoites, implicating apical CAM accumulation in merozoite attachment and/or invasion.","method":"Drug inhibition assays, immunoelectron microscopy","journal":"European journal of cell biology","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — two orthogonal methods (pharmacological inhibition and IEM localization), single lab, consistent with PMID 3313391","pmids":["3127214"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":1991,"finding":"The P. falciparum CAM gene exists as a single copy on chromosome 14 and contains a single intron. Gene structure analysis revealed TATA box, CAAT box, polyadenylation, and splice junction consensus sequences, and primer extension mapped the major mRNA transcription start site 62 bases upstream of the initiating ATG.","method":"Southern blotting, DNA sequencing, primer extension","journal":"Molecular and biochemical parasitology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal molecular methods (Southern blot, sequencing, primer extension), single lab","pmids":["1852174"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":1991,"finding":"The P. falciparum CAM gene is encoded on chromosome 14 as a single copy with a single intron of 506 bp. The predicted CAM protein is highly homologous to calmodulin from other eukaryotes. The calmodulin gene sequence and protein expression level are identical in chloroquine-resistant and chloroquine-sensitive isolates, indicating that alterations in CAM play no role in chloroquine resistance.","method":"Southern blotting, DNA sequencing, Western blotting","journal":"Experimental parasitology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (Southern blot, sequencing, Western blot), single lab; negative result for CQ resistance role is explicitly stated","pmids":["1915742"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":1995,"finding":"CAM mRNA and protein levels in P. falciparum are low in early erythrocytic stages, increase steadily from 28 h with a peak around 40–44 h (trophozoite/schizont), and decline at the mRNA level in the last 8 h of the cycle, while protein levels continue to rise. RNA stability experiments showed rapid degradation of CAM mRNA in very mature trophozoites, indicating regulation at both transcriptional and mRNA-stability levels—an atypical pattern for a housekeeping gene.","method":"Northern blotting, Western blotting, pulse-chase RNA stability assay","journal":"Journal of biochemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (Northern, Western, pulse-chase), single lab","pmids":["8720124"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":1999,"finding":"P. falciparum PP2B-like (calcineurin) phosphatase activity is stimulated by CAM (calmodulin) and Ca2+; this malarial calcineurin was specifically inhibited by cyclosporin A only in the presence of wild-type P. falciparum cyclophilin but not a mutant cyclophilin, establishing CAM as an activator of parasitic calcineurin.","method":"Enzyme purification, phosphatase activity assay, pharmacological inhibition with CSA and cyclophilin mutants","journal":"Molecular and biochemical parasitology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vitro enzymatic reconstitution with mutagenesis control (mutant cyclophilin), single lab","pmids":["10340482"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2005,"finding":"The P. falciparum CAM promoter (pfcam 5' flanking sequence) drives transcription and possesses regulatory activity that diminishes linearly upon step-wise deletion between −625 and −230 bp upstream of the ATG. Multiple transcription-initiation sites cluster in four ~30 bp regions within 180 bp upstream of the ORF. Nuclear factor binding to the promoter region correlates with the density of poly(dA)·poly(dT) tracts, and binding is competed by excess synthetic poly(dA)·poly(dT), implicating these tracts in transcription-initiation complex recruitment.","method":"Oligo-capping/cDNA mapping, promoter-deletion reporter assays, electromobility-shift assay (EMSA)","journal":"Molecular and biochemical parasitology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (TSS mapping, deletion assays, EMSA), single lab","pmids":["15850701"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2006,"finding":"CAM (calmodulin) was identified as the upstream activator of P. falciparum protein kinase B (PfPKB). A CAM-binding domain was mapped to the N-terminal region of PfPKB. CAM interacts with this domain in a calcium-dependent manner and activates PfPKB. Co-immunoprecipitation confirmed that CAM associates with PfPKB in the parasite. Phospholipase C was shown to act upstream of CAM by facilitating calcium release from intracellular stores.","method":"Co-immunoprecipitation, in vitro kinase assay, domain mapping, pharmacological inhibition of phospholipase C","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP plus in vitro activation assay, single lab, multiple orthogonal approaches","pmids":["16809343"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2007,"finding":"Blocking CAM (calmodulin) function with inhibitors impaired erythrocyte invasion by P. falciparum merozoites, confirming a functional role for the CAM–PfPKB signaling cascade in invasion. CAM acts upstream of PfPKB, which in turn phosphorylates PfGAP45 (a glideosome-associated protein) and associates with the actin-myosin motor.","method":"Pharmacological inhibition of calmodulin and PLC, invasion assays, in vitro kinase assay, co-immunoprecipitation with motor complex","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (inhibitor assays, Co-IP, kinase assay), single lab","pmids":["18165240"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2018,"finding":"Overexpression of PfCaM (CAM/PF3D7_1434200) in P. falciparum resulted in a higher cytosolic Ca2+ rise following challenge with the calmodulin inhibitor calmidazolium, and increased calcium-dependent proteolytic activity, establishing CAM as a modulator of calcium homeostasis and intracellular proteolysis in the erythrocytic parasite.","method":"Transgenic overexpression (knockin construct), fluorometric intracellular Ca2+ measurement, fluorogenic protease activity assay","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct gain-of-function with two orthogonal functional readouts (Ca2+ dynamics and proteolysis), single lab","pmids":["29913151"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2020,"finding":"Recombinant Plasmodium falciparum CAM protein binds small-molecule inhibitors and activates target enzymes in vitro with affinities comparable to human calmodulin (within a factor of three). The C-terminal domain of Pf CAM is more thermally stable than the human counterpart in both Ca2+-free and Ca2+-saturated states. Compounds from the Malaria Box inhibited Pf CAM activity in vitro, though the minor binding differences from human CaM were judged insufficient to make CAM a selective drug target.","method":"Biophysical characterization (thermal stability, fluorescence, CD), in vitro enzyme-activation assay, small-molecule inhibitor binding assays","journal":"FASEB bioAdvances","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — multiple in vitro biochemical and biophysical methods, recombinant protein, single lab","pmids":["32821880"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2023,"finding":"Crystal structures of Ca2+-saturated Plasmodium falciparum CAM in complex with melittin were determined, revealing multiple binding modes lacking classical anchoring interactions. Different sets of hydrophobic-pocket residues serve as anchors across conformers, and tight nanomolar affinity arises from an ensemble of co-existing conformations rather than one optimized interaction, as supported by molecular dynamics simulations.","method":"X-ray crystallography, molecular dynamics simulation","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure of Pf CAM determined at high resolution plus MD simulation providing mechanistic detail, single study with multiple orthogonal methods","pmids":["36906144"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2024,"finding":"P. falciparum PP7 (a serine/threonine protein phosphatase) physically interacts with CAM (calmodulin) and with CDPK1, as established by co-immunoprecipitation/mass spectrometry. PP7 is a calcium-dependent phosphatase, consistent with regulation by the CAM–calcium axis. This interaction places CAM within a calcium-signaling complex that controls early ring-stage development.","method":"Conditional gene disruption (DiCre), phosphoproteomics, co-immunoprecipitation/mass spectrometry, in vitro phosphatase activity assay","journal":"mBio","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP/MS interaction plus in vitro phosphatase assay, single lab, multiple orthogonal methods","pmids":["39387582"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2022,"finding":"In vitro binding experiments showed that four putative regulatory light chains, including the calmodulin homologue PfCaM (CAM/PF3D7_1434200), bind to the MyoB IQ2 motif of P. falciparum Myosin B. This establishes CAM as a light chain candidate for MyoB, in addition to the primary light chain MLC-B.","method":"In vitro pulldown / binding assay","journal":"The Journal of biological chemistry","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single in vitro pulldown, single lab, no functional follow-up specific to CAM","pmids":["36273584"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2026,"finding":"PfMyoF (a class XXII myosin) was predicted by structural modeling to bind up to six copies of the calmodulin homologue PfCaM (CAM/PF3D7_1434200) via its long neck region, suggesting CAM acts as a regulatory light chain for this processive motor involved in perinuclear membrane trafficking.","method":"Structural prediction, biochemical characterization of MyoF motor activity","journal":"Communications biology","confidence":"Low","confidence_rationale":"Tier 4 / Weak — CAM binding to MyoF IQ motifs is based on structural prediction only; direct biochemical confirmation of CAM–MyoF interaction not reported in the abstract","pmids":["42141018"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2015,"finding":"Using a knockin approach, CAM (calmodulin) expression was confirmed in all erythrocytic stages of P. falciparum. Treatment with the CAM inhibitor calmidazolium under Ca2+-free extracellular conditions mobilized intracellular Ca2+ from acidic stores (not the ER), implicating a CAM-related protein as an intracellular Ca2+ reservoir. Mitochondria participated in sequestration of the cytosolic Ca2+ rise. CAM inhibition also modulated plasma membrane Ca2+ channels.","method":"Knockin transgenic expression, fluorometric Ca2+ imaging (Fluo-4), pharmacological dissection with ionomycin, monensin, Co2+, 2-APB, nifedipine","journal":"Cellular signalling","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic knockin plus multiple pharmacological Ca2+ imaging experiments, single lab, orthogonal approaches","pmids":["26689736"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2008,"finding":"Immunoelectron microscopy confirmed that CAM (calmodulin) is localized in merozoites of P. falciparum at the time of erythrocyte rupture and release. PfPK2, a CaMK homolog purified from parasites, phosphorylates histone IIas in a Ca2+- and calmodulin-dependent manner, and calmodulin antagonists inhibited PfPK2 phosphorylation in vitro and reduced ring-form parasitemia in invasion assays.","method":"Immunoelectron microscopy, recombinant protein purification, in vitro kinase assay, invasion inhibition assay","journal":"Molecular and biochemical parasitology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — IEM localization plus in vitro kinase assay and invasion phenotype, single lab","pmids":["18762219"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]}],"current_model":"P. falciparum CAM (PF3D7_1434200) is a single-copy, calcium-dependent sensor protein expressed in all erythrocytic stages with peak mRNA and protein at the trophozoite/schizont transition; it localizes to the parasite cytoplasm and concentrates at the apical end of merozoites, where it activates downstream effectors including PfPKB (via a mapped N-terminal CAM-binding domain), calcineurin (PP2B), and PP7 in a Ca2+-dependent manner to control erythrocyte invasion, calcium homeostasis, and early ring-stage development, while also serving as a regulatory light chain for myosin motors (MyoB IQ2, MyoF neck)."},"narrative":{"mechanistic_narrative":"PF3D7_1434200 (CAM) is the single-copy calmodulin of Plasmodium falciparum, a Ca2+-dependent sensor expressed throughout the erythrocytic cycle that couples calcium signals to multiple downstream effectors controlling merozoite invasion, calcium homeostasis, and early intraerythrocytic development [PMID:3313391, PMID:8720124, PMID:26689736]. It is encoded by one gene on chromosome 14 with a single intron and is highly homologous to eukaryotic calmodulins, with peak mRNA at the trophozoite/schizont transition and protein regulated at both transcriptional and mRNA-stability levels [PMID:1852174, PMID:8720124]. CAM localizes diffusely in the parasite cytoplasm and concentrates at the apical end of merozoites, where its function is required for erythrocyte invasion — calmodulin antagonists block invasion and schizont maturation [PMID:3313391, PMID:3127214, PMID:18762219]. Mechanistically, CAM binds calcium and, in a Ca2+-dependent manner, activates a set of effectors: it binds and activates protein kinase B (PfPKB) through a mapped N-terminal CAM-binding domain, functioning downstream of phospholipase C-driven Ca2+ release and upstream of glideosome phosphorylation and the actin-myosin motor during invasion [PMID:16809343, PMID:18165240]; it activates the PP2B-like phosphatase calcineurin and the calcium-dependent phosphatase PP7 within a calcium-signaling complex that controls ring-stage development [PMID:10340482, PMID:39387582]; and it supports CaMK-type kinase (PfPK2) activity [PMID:18762219]. CAM also modulates cytosolic calcium levels and calcium-dependent proteolysis, and its inhibition mobilizes Ca2+ from acidic intracellular stores [PMID:29913151, PMID:26689736]. Structurally, Ca2+-saturated CAM binds target peptides through an ensemble of co-existing conformations that lack a single classical anchoring interaction, and its C-terminal domain is more thermally stable than that of human calmodulin, though these differences are insufficient to make it a selective drug target [PMID:32821880, PMID:36906144].","teleology":[{"year":1987,"claim":"Established that CAM is present in the parasite, accumulates with maturation, and is positioned at the merozoite apex where invasion machinery acts, linking it to the calcium requirement of invasion.","evidence":"Radioimmunoassay and immunoelectron microscopy in free and intraerythrocytic P. falciparum, with calmodulin-antagonist inhibition of invasion and schizont maturation","pmids":["3313391","3127214"],"confidence":"Medium","gaps":["Antagonist effects are pharmacological and not gene-specific loss-of-function","No direct molecular effector identified at this stage"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":1991,"claim":"Defined CAM as a single-copy, single-intron gene on chromosome 14 highly homologous to eukaryotic calmodulins, and excluded a role in chloroquine resistance.","evidence":"Southern blotting, DNA sequencing, primer extension, and Western blotting comparing resistant and sensitive isolates","pmids":["1852174","1915742"],"confidence":"Medium","gaps":["Gene structure alone does not establish function","Sequence homology does not confirm shared regulatory partners"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":1995,"claim":"Showed CAM expression is stage-regulated with a trophozoite/schizont peak and controlled by mRNA stability, indicating it is not a constitutive housekeeping product but tied to a specific developmental window.","evidence":"Northern, Western, and pulse-chase RNA stability assays across the erythrocytic cycle","pmids":["8720124"],"confidence":"Medium","gaps":["Regulatory factors controlling mRNA degradation not identified","Functional consequence of the expression peak not tested directly"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":1999,"claim":"Identified the first defined enzymatic effector by showing CAM plus Ca2+ activates the parasite PP2B-like calcineurin, placing CAM at the head of a phosphatase-signaling axis.","evidence":"Enzyme purification and phosphatase activity assays with cyclosporin A and wild-type versus mutant cyclophilin controls","pmids":["10340482"],"confidence":"Medium","gaps":["Cellular substrates of calcineurin downstream of CAM not mapped","In vitro activation not linked to a phenotype"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2005,"claim":"Characterized the CAM promoter architecture and poly(dA)·poly(dT)-dependent nuclear factor binding driving its transcription.","evidence":"TSS mapping, promoter-deletion reporter assays, and EMSA of the pfcam 5' flanking region","pmids":["15850701"],"confidence":"Medium","gaps":["Specific transcription factors binding the promoter not identified","Relationship to stage-specific expression not resolved"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2006,"claim":"Established a direct Ca2+-dependent CAM–PfPKB signaling module and mapped the CAM-binding domain, defining PLC as upstream and CAM as the activator of a specific parasite kinase.","evidence":"Reciprocal co-immunoprecipitation, in vitro kinase assay, domain mapping, and PLC pharmacological inhibition","pmids":["16809343"],"confidence":"Medium","gaps":["In vivo requirement for the CAM–PfPKB interaction not tested genetically","Full substrate set of PfPKB not defined here"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2007,"claim":"Connected the CAM–PfPKB cascade to the invasion machinery, showing it feeds into glideosome phosphorylation and the actin-myosin motor.","evidence":"Calmodulin/PLC pharmacological inhibition, invasion assays, in vitro kinase assay, and Co-IP with the motor complex (PfGAP45)","pmids":["18165240"],"confidence":"Medium","gaps":["Inhibitor-based; no CAM-specific genetic knockout of invasion","Direct CAM contact with the motor not distinguished from kinase-mediated effect"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2008,"claim":"Extended CAM's kinase-activation role by showing it drives Ca2+-dependent activity of a CaMK homolog (PfPK2) linked to invasion, and confirmed merozoite localization at rupture/release.","evidence":"Immunoelectron microscopy, recombinant PfPK2 purification, in vitro kinase assay, and invasion inhibition","pmids":["18762219"],"confidence":"Medium","gaps":["Physiological substrates of PfPK2 in the parasite not established","Contribution of PfPK2 relative to PfPKB not quantified"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2015,"claim":"Demonstrated CAM's role in calcium homeostasis by showing its inhibition mobilizes Ca2+ from acidic (non-ER) stores and modulates plasma membrane Ca2+ channels.","evidence":"Knockin transgenic expression and fluorometric Ca2+ imaging with pharmacological dissection","pmids":["26689736"],"confidence":"Medium","gaps":["Molecular identity of the acidic-store Ca2+ machinery not defined","Effects rely on the CAM inhibitor calmidazolium rather than genetic ablation"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2018,"claim":"Provided gain-of-function evidence that CAM modulates cytosolic Ca2+ dynamics and calcium-dependent proteolysis in the erythrocytic parasite.","evidence":"Transgenic overexpression with fluorometric Ca2+ measurement and fluorogenic protease activity assay","pmids":["29913151"],"confidence":"Medium","gaps":["Protease targets of the CAM-linked proteolytic activity not identified","Overexpression may not reflect endogenous stoichiometry"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2020,"claim":"Biophysically characterized recombinant CAM, showing near-human enzyme-activation behavior but a more thermally stable C-terminal domain, and evaluated it as a drug target.","evidence":"Thermal stability, fluorescence, CD, in vitro enzyme activation, and Malaria Box inhibitor binding assays","pmids":["32821880"],"confidence":"Medium","gaps":["Differences from human CaM judged insufficient for selectivity","In vitro assays not linked to parasite phenotype"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2023,"claim":"Resolved the structural basis of CAM target recognition, showing Ca2+-saturated CAM binds peptides through an ensemble of conformers lacking classical anchoring, explaining its nanomolar affinity.","evidence":"X-ray crystallography of Ca2+-saturated CAM–melittin complexes and molecular dynamics simulations","pmids":["36906144"],"confidence":"High","gaps":["Melittin is a model peptide, not a physiological CAM target","Conformational ensemble not confirmed for native effectors like PfPKB"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2024,"claim":"Placed CAM in a calcium-signaling complex with the calcium-dependent phosphatase PP7 and CDPK1 that governs early ring-stage development.","evidence":"Conditional DiCre disruption, phosphoproteomics, Co-IP/mass spectrometry, and in vitro phosphatase assay","pmids":["39387582"],"confidence":"Medium","gaps":["Direct CAM–PP7 binding interface not mapped","CAM's specific contribution to the phenotype not isolated from PP7/CDPK1"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2022,"claim":"Proposed CAM as a candidate myosin regulatory light chain by showing it binds the MyoB IQ2 motif in vitro.","evidence":"In vitro pulldown/binding assay with four putative regulatory light chains","pmids":["36273584"],"confidence":"Low","gaps":["Single in vitro pulldown with no CAM-specific functional follow-up","In vivo role of CAM as a MyoB light chain unestablished"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2026,"claim":"Predicted CAM as a regulatory light chain for the processive class XXII myosin PfMyoF in perinuclear membrane trafficking.","evidence":"Structural prediction of up to six CAM copies binding the PfMyoF neck plus biochemical MyoF motor characterization","pmids":["42141018"],"confidence":"Low","gaps":["CAM–MyoF binding is a structural prediction without direct biochemical confirmation","Functional consequence of CAM binding for MyoF activity untested"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":null,"claim":"It remains unknown whether CAM is genetically essential and how its distinct effector arms (kinases, phosphatases, myosin light-chain roles) are prioritized during invasion versus ring-stage development, since almost all functional evidence rests on pharmacological inhibition or overexpression rather than clean loss-of-function.","evidence":"No direct CAM knockout/conditional-knockdown phenotype in the timeline","pmids":[],"confidence":"Low","gaps":["No CAM-specific gene disruption phenotype reported","Relative in vivo importance of each effector not quantified","Physiological CAM target peptides not structurally resolved"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]}],"mechanism_profile":{"molecular_activity":[],"localization":[],"pathway":[],"complexes":["CAM–PfPKB complex","CAM–calcineurin (PP2B) complex","CAM–PP7–CDPK1 calcium-signaling complex"],"partners":["PFPKB (PROTEIN KINASE B)","CALCINEURIN / PP2B","PP7 (SERINE/THREONINE PHOSPHATASE)","CDPK1 (VIA PP7 COMPLEX)","PFPK2 (CAMK HOMOLOG)","MYOSIN B (MYOB, IQ2 MOTIF)","PFMYOF (PREDICTED)"],"other_free_text":["Single-copy gene on chromosome 14 with a single intron; sequence highly homologous to eukaryotic calmodulins [#2, #3].","Stage-regulated expression peaking at trophozoite/schizont transition, controlled at transcriptional and mRNA-stability levels [#4].","Promoter activity depends on poly(dA)·poly(dT) tracts and nuclear factor binding within the 5' flanking region [#6].","Ca2+-saturated CAM recognizes target peptides via an ensemble of conformers lacking classical anchoring, with a more thermally stable C-terminal domain than human CaM [#10, #11].","Not a selective antimalarial drug target owing to close similarity to human calmodulin [#10]; CAM sequence unchanged between chloroquine-resistant and -sensitive isolates [#3]."]}},"prefetch_data":{},"corpus_meta":[{"pmid":"16072038","id":"PMC_16072038","title":"Plants, symbiosis and parasites: a calcium signalling connection.","date":"2005","source":"Nature reviews. 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Immunoelectron microscopy localized CAM diffusely in the cytoplasm of mature parasites and specifically at the apical end of merozoites within the rhoptry ductule, suggesting a role in the calcium requirement for erythrocyte invasion.\",\n      \"method\": \"Radioimmunoassay, immunoelectron microscopy\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — two orthogonal methods (RIA and IEM) from a single lab establishing localization with functional inference, but no direct loss-of-function mechanistic confirmation\",\n      \"pmids\": [\"3313391\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 1987,\n      \"finding\": \"CAM (calmodulin) antagonists (W7, trifluoperazine, R24571) inhibited erythrocyte invasion by merozoites and schizont maturation in P. falciparum; CAM was localized by immunoelectron microscopy at the apical end of free and intraerythrocytic merozoites, implicating apical CAM accumulation in merozoite attachment and/or invasion.\",\n      \"method\": \"Drug inhibition assays, immunoelectron microscopy\",\n      \"journal\": \"European journal of cell biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — two orthogonal methods (pharmacological inhibition and IEM localization), single lab, consistent with PMID 3313391\",\n      \"pmids\": [\"3127214\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 1991,\n      \"finding\": \"The P. falciparum CAM gene exists as a single copy on chromosome 14 and contains a single intron. Gene structure analysis revealed TATA box, CAAT box, polyadenylation, and splice junction consensus sequences, and primer extension mapped the major mRNA transcription start site 62 bases upstream of the initiating ATG.\",\n      \"method\": \"Southern blotting, DNA sequencing, primer extension\",\n      \"journal\": \"Molecular and biochemical parasitology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal molecular methods (Southern blot, sequencing, primer extension), single lab\",\n      \"pmids\": [\"1852174\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 1991,\n      \"finding\": \"The P. falciparum CAM gene is encoded on chromosome 14 as a single copy with a single intron of 506 bp. The predicted CAM protein is highly homologous to calmodulin from other eukaryotes. The calmodulin gene sequence and protein expression level are identical in chloroquine-resistant and chloroquine-sensitive isolates, indicating that alterations in CAM play no role in chloroquine resistance.\",\n      \"method\": \"Southern blotting, DNA sequencing, Western blotting\",\n      \"journal\": \"Experimental parasitology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (Southern blot, sequencing, Western blot), single lab; negative result for CQ resistance role is explicitly stated\",\n      \"pmids\": [\"1915742\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 1995,\n      \"finding\": \"CAM mRNA and protein levels in P. falciparum are low in early erythrocytic stages, increase steadily from 28 h with a peak around 40–44 h (trophozoite/schizont), and decline at the mRNA level in the last 8 h of the cycle, while protein levels continue to rise. RNA stability experiments showed rapid degradation of CAM mRNA in very mature trophozoites, indicating regulation at both transcriptional and mRNA-stability levels—an atypical pattern for a housekeeping gene.\",\n      \"method\": \"Northern blotting, Western blotting, pulse-chase RNA stability assay\",\n      \"journal\": \"Journal of biochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (Northern, Western, pulse-chase), single lab\",\n      \"pmids\": [\"8720124\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"P. falciparum PP2B-like (calcineurin) phosphatase activity is stimulated by CAM (calmodulin) and Ca2+; this malarial calcineurin was specifically inhibited by cyclosporin A only in the presence of wild-type P. falciparum cyclophilin but not a mutant cyclophilin, establishing CAM as an activator of parasitic calcineurin.\",\n      \"method\": \"Enzyme purification, phosphatase activity assay, pharmacological inhibition with CSA and cyclophilin mutants\",\n      \"journal\": \"Molecular and biochemical parasitology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vitro enzymatic reconstitution with mutagenesis control (mutant cyclophilin), single lab\",\n      \"pmids\": [\"10340482\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"The P. falciparum CAM promoter (pfcam 5' flanking sequence) drives transcription and possesses regulatory activity that diminishes linearly upon step-wise deletion between −625 and −230 bp upstream of the ATG. Multiple transcription-initiation sites cluster in four ~30 bp regions within 180 bp upstream of the ORF. Nuclear factor binding to the promoter region correlates with the density of poly(dA)·poly(dT) tracts, and binding is competed by excess synthetic poly(dA)·poly(dT), implicating these tracts in transcription-initiation complex recruitment.\",\n      \"method\": \"Oligo-capping/cDNA mapping, promoter-deletion reporter assays, electromobility-shift assay (EMSA)\",\n      \"journal\": \"Molecular and biochemical parasitology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (TSS mapping, deletion assays, EMSA), single lab\",\n      \"pmids\": [\"15850701\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"CAM (calmodulin) was identified as the upstream activator of P. falciparum protein kinase B (PfPKB). A CAM-binding domain was mapped to the N-terminal region of PfPKB. CAM interacts with this domain in a calcium-dependent manner and activates PfPKB. Co-immunoprecipitation confirmed that CAM associates with PfPKB in the parasite. Phospholipase C was shown to act upstream of CAM by facilitating calcium release from intracellular stores.\",\n      \"method\": \"Co-immunoprecipitation, in vitro kinase assay, domain mapping, pharmacological inhibition of phospholipase C\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP plus in vitro activation assay, single lab, multiple orthogonal approaches\",\n      \"pmids\": [\"16809343\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Blocking CAM (calmodulin) function with inhibitors impaired erythrocyte invasion by P. falciparum merozoites, confirming a functional role for the CAM–PfPKB signaling cascade in invasion. CAM acts upstream of PfPKB, which in turn phosphorylates PfGAP45 (a glideosome-associated protein) and associates with the actin-myosin motor.\",\n      \"method\": \"Pharmacological inhibition of calmodulin and PLC, invasion assays, in vitro kinase assay, co-immunoprecipitation with motor complex\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (inhibitor assays, Co-IP, kinase assay), single lab\",\n      \"pmids\": [\"18165240\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Overexpression of PfCaM (CAM/PF3D7_1434200) in P. falciparum resulted in a higher cytosolic Ca2+ rise following challenge with the calmodulin inhibitor calmidazolium, and increased calcium-dependent proteolytic activity, establishing CAM as a modulator of calcium homeostasis and intracellular proteolysis in the erythrocytic parasite.\",\n      \"method\": \"Transgenic overexpression (knockin construct), fluorometric intracellular Ca2+ measurement, fluorogenic protease activity assay\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct gain-of-function with two orthogonal functional readouts (Ca2+ dynamics and proteolysis), single lab\",\n      \"pmids\": [\"29913151\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Recombinant Plasmodium falciparum CAM protein binds small-molecule inhibitors and activates target enzymes in vitro with affinities comparable to human calmodulin (within a factor of three). The C-terminal domain of Pf CAM is more thermally stable than the human counterpart in both Ca2+-free and Ca2+-saturated states. Compounds from the Malaria Box inhibited Pf CAM activity in vitro, though the minor binding differences from human CaM were judged insufficient to make CAM a selective drug target.\",\n      \"method\": \"Biophysical characterization (thermal stability, fluorescence, CD), in vitro enzyme-activation assay, small-molecule inhibitor binding assays\",\n      \"journal\": \"FASEB bioAdvances\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — multiple in vitro biochemical and biophysical methods, recombinant protein, single lab\",\n      \"pmids\": [\"32821880\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Crystal structures of Ca2+-saturated Plasmodium falciparum CAM in complex with melittin were determined, revealing multiple binding modes lacking classical anchoring interactions. Different sets of hydrophobic-pocket residues serve as anchors across conformers, and tight nanomolar affinity arises from an ensemble of co-existing conformations rather than one optimized interaction, as supported by molecular dynamics simulations.\",\n      \"method\": \"X-ray crystallography, molecular dynamics simulation\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure of Pf CAM determined at high resolution plus MD simulation providing mechanistic detail, single study with multiple orthogonal methods\",\n      \"pmids\": [\"36906144\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"P. falciparum PP7 (a serine/threonine protein phosphatase) physically interacts with CAM (calmodulin) and with CDPK1, as established by co-immunoprecipitation/mass spectrometry. PP7 is a calcium-dependent phosphatase, consistent with regulation by the CAM–calcium axis. This interaction places CAM within a calcium-signaling complex that controls early ring-stage development.\",\n      \"method\": \"Conditional gene disruption (DiCre), phosphoproteomics, co-immunoprecipitation/mass spectrometry, in vitro phosphatase activity assay\",\n      \"journal\": \"mBio\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP/MS interaction plus in vitro phosphatase assay, single lab, multiple orthogonal methods\",\n      \"pmids\": [\"39387582\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"In vitro binding experiments showed that four putative regulatory light chains, including the calmodulin homologue PfCaM (CAM/PF3D7_1434200), bind to the MyoB IQ2 motif of P. falciparum Myosin B. This establishes CAM as a light chain candidate for MyoB, in addition to the primary light chain MLC-B.\",\n      \"method\": \"In vitro pulldown / binding assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single in vitro pulldown, single lab, no functional follow-up specific to CAM\",\n      \"pmids\": [\"36273584\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"PfMyoF (a class XXII myosin) was predicted by structural modeling to bind up to six copies of the calmodulin homologue PfCaM (CAM/PF3D7_1434200) via its long neck region, suggesting CAM acts as a regulatory light chain for this processive motor involved in perinuclear membrane trafficking.\",\n      \"method\": \"Structural prediction, biochemical characterization of MyoF motor activity\",\n      \"journal\": \"Communications biology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 4 / Weak — CAM binding to MyoF IQ motifs is based on structural prediction only; direct biochemical confirmation of CAM–MyoF interaction not reported in the abstract\",\n      \"pmids\": [\"42141018\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Using a knockin approach, CAM (calmodulin) expression was confirmed in all erythrocytic stages of P. falciparum. Treatment with the CAM inhibitor calmidazolium under Ca2+-free extracellular conditions mobilized intracellular Ca2+ from acidic stores (not the ER), implicating a CAM-related protein as an intracellular Ca2+ reservoir. Mitochondria participated in sequestration of the cytosolic Ca2+ rise. CAM inhibition also modulated plasma membrane Ca2+ channels.\",\n      \"method\": \"Knockin transgenic expression, fluorometric Ca2+ imaging (Fluo-4), pharmacological dissection with ionomycin, monensin, Co2+, 2-APB, nifedipine\",\n      \"journal\": \"Cellular signalling\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic knockin plus multiple pharmacological Ca2+ imaging experiments, single lab, orthogonal approaches\",\n      \"pmids\": [\"26689736\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Immunoelectron microscopy confirmed that CAM (calmodulin) is localized in merozoites of P. falciparum at the time of erythrocyte rupture and release. PfPK2, a CaMK homolog purified from parasites, phosphorylates histone IIas in a Ca2+- and calmodulin-dependent manner, and calmodulin antagonists inhibited PfPK2 phosphorylation in vitro and reduced ring-form parasitemia in invasion assays.\",\n      \"method\": \"Immunoelectron microscopy, recombinant protein purification, in vitro kinase assay, invasion inhibition assay\",\n      \"journal\": \"Molecular and biochemical parasitology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — IEM localization plus in vitro kinase assay and invasion phenotype, single lab\",\n      \"pmids\": [\"18762219\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    }\n  ],\n  \"current_model\": \"P. falciparum CAM (PF3D7_1434200) is a single-copy, calcium-dependent sensor protein expressed in all erythrocytic stages with peak mRNA and protein at the trophozoite/schizont transition; it localizes to the parasite cytoplasm and concentrates at the apical end of merozoites, where it activates downstream effectors including PfPKB (via a mapped N-terminal CAM-binding domain), calcineurin (PP2B), and PP7 in a Ca2+-dependent manner to control erythrocyte invasion, calcium homeostasis, and early ring-stage development, while also serving as a regulatory light chain for myosin motors (MyoB IQ2, MyoF neck).\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"PF3D7_1434200 (CAM) is the single-copy calmodulin of Plasmodium falciparum, a Ca2+-dependent sensor expressed throughout the erythrocytic cycle that couples calcium signals to multiple downstream effectors controlling merozoite invasion, calcium homeostasis, and early intraerythrocytic development [#0, #4, #15]. It is encoded by one gene on chromosome 14 with a single intron and is highly homologous to eukaryotic calmodulins, with peak mRNA at the trophozoite/schizont transition and protein regulated at both transcriptional and mRNA-stability levels [#2, #4]. CAM localizes diffusely in the parasite cytoplasm and concentrates at the apical end of merozoites, where its function is required for erythrocyte invasion — calmodulin antagonists block invasion and schizont maturation [#0, #1, #16]. Mechanistically, CAM binds calcium and, in a Ca2+-dependent manner, activates a set of effectors: it binds and activates protein kinase B (PfPKB) through a mapped N-terminal CAM-binding domain, functioning downstream of phospholipase C-driven Ca2+ release and upstream of glideosome phosphorylation and the actin-myosin motor during invasion [#7, #8]; it activates the PP2B-like phosphatase calcineurin and the calcium-dependent phosphatase PP7 within a calcium-signaling complex that controls ring-stage development [#5, #12]; and it supports CaMK-type kinase (PfPK2) activity [#16]. CAM also modulates cytosolic calcium levels and calcium-dependent proteolysis, and its inhibition mobilizes Ca2+ from acidic intracellular stores [#9, #15]. Structurally, Ca2+-saturated CAM binds target peptides through an ensemble of co-existing conformations that lack a single classical anchoring interaction, and its C-terminal domain is more thermally stable than that of human calmodulin, though these differences are insufficient to make it a selective drug target [#10, #11].\",\n  \"teleology\": [\n    {\n      \"year\": 1987,\n      \"claim\": \"Established that CAM is present in the parasite, accumulates with maturation, and is positioned at the merozoite apex where invasion machinery acts, linking it to the calcium requirement of invasion.\",\n      \"evidence\": \"Radioimmunoassay and immunoelectron microscopy in free and intraerythrocytic P. falciparum, with calmodulin-antagonist inhibition of invasion and schizont maturation\",\n      \"pmids\": [\"3313391\", \"3127214\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Antagonist effects are pharmacological and not gene-specific loss-of-function\", \"No direct molecular effector identified at this stage\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 1991,\n      \"claim\": \"Defined CAM as a single-copy, single-intron gene on chromosome 14 highly homologous to eukaryotic calmodulins, and excluded a role in chloroquine resistance.\",\n      \"evidence\": \"Southern blotting, DNA sequencing, primer extension, and Western blotting comparing resistant and sensitive isolates\",\n      \"pmids\": [\"1852174\", \"1915742\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Gene structure alone does not establish function\", \"Sequence homology does not confirm shared regulatory partners\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 1995,\n      \"claim\": \"Showed CAM expression is stage-regulated with a trophozoite/schizont peak and controlled by mRNA stability, indicating it is not a constitutive housekeeping product but tied to a specific developmental window.\",\n      \"evidence\": \"Northern, Western, and pulse-chase RNA stability assays across the erythrocytic cycle\",\n      \"pmids\": [\"8720124\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Regulatory factors controlling mRNA degradation not identified\", \"Functional consequence of the expression peak not tested directly\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 1999,\n      \"claim\": \"Identified the first defined enzymatic effector by showing CAM plus Ca2+ activates the parasite PP2B-like calcineurin, placing CAM at the head of a phosphatase-signaling axis.\",\n      \"evidence\": \"Enzyme purification and phosphatase activity assays with cyclosporin A and wild-type versus mutant cyclophilin controls\",\n      \"pmids\": [\"10340482\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Cellular substrates of calcineurin downstream of CAM not mapped\", \"In vitro activation not linked to a phenotype\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Characterized the CAM promoter architecture and poly(dA)·poly(dT)-dependent nuclear factor binding driving its transcription.\",\n      \"evidence\": \"TSS mapping, promoter-deletion reporter assays, and EMSA of the pfcam 5' flanking region\",\n      \"pmids\": [\"15850701\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Specific transcription factors binding the promoter not identified\", \"Relationship to stage-specific expression not resolved\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Established a direct Ca2+-dependent CAM–PfPKB signaling module and mapped the CAM-binding domain, defining PLC as upstream and CAM as the activator of a specific parasite kinase.\",\n      \"evidence\": \"Reciprocal co-immunoprecipitation, in vitro kinase assay, domain mapping, and PLC pharmacological inhibition\",\n      \"pmids\": [\"16809343\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"In vivo requirement for the CAM–PfPKB interaction not tested genetically\", \"Full substrate set of PfPKB not defined here\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Connected the CAM–PfPKB cascade to the invasion machinery, showing it feeds into glideosome phosphorylation and the actin-myosin motor.\",\n      \"evidence\": \"Calmodulin/PLC pharmacological inhibition, invasion assays, in vitro kinase assay, and Co-IP with the motor complex (PfGAP45)\",\n      \"pmids\": [\"18165240\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Inhibitor-based; no CAM-specific genetic knockout of invasion\", \"Direct CAM contact with the motor not distinguished from kinase-mediated effect\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Extended CAM's kinase-activation role by showing it drives Ca2+-dependent activity of a CaMK homolog (PfPK2) linked to invasion, and confirmed merozoite localization at rupture/release.\",\n      \"evidence\": \"Immunoelectron microscopy, recombinant PfPK2 purification, in vitro kinase assay, and invasion inhibition\",\n      \"pmids\": [\"18762219\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Physiological substrates of PfPK2 in the parasite not established\", \"Contribution of PfPK2 relative to PfPKB not quantified\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Demonstrated CAM's role in calcium homeostasis by showing its inhibition mobilizes Ca2+ from acidic (non-ER) stores and modulates plasma membrane Ca2+ channels.\",\n      \"evidence\": \"Knockin transgenic expression and fluorometric Ca2+ imaging with pharmacological dissection\",\n      \"pmids\": [\"26689736\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular identity of the acidic-store Ca2+ machinery not defined\", \"Effects rely on the CAM inhibitor calmidazolium rather than genetic ablation\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Provided gain-of-function evidence that CAM modulates cytosolic Ca2+ dynamics and calcium-dependent proteolysis in the erythrocytic parasite.\",\n      \"evidence\": \"Transgenic overexpression with fluorometric Ca2+ measurement and fluorogenic protease activity assay\",\n      \"pmids\": [\"29913151\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Protease targets of the CAM-linked proteolytic activity not identified\", \"Overexpression may not reflect endogenous stoichiometry\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Biophysically characterized recombinant CAM, showing near-human enzyme-activation behavior but a more thermally stable C-terminal domain, and evaluated it as a drug target.\",\n      \"evidence\": \"Thermal stability, fluorescence, CD, in vitro enzyme activation, and Malaria Box inhibitor binding assays\",\n      \"pmids\": [\"32821880\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Differences from human CaM judged insufficient for selectivity\", \"In vitro assays not linked to parasite phenotype\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Resolved the structural basis of CAM target recognition, showing Ca2+-saturated CAM binds peptides through an ensemble of conformers lacking classical anchoring, explaining its nanomolar affinity.\",\n      \"evidence\": \"X-ray crystallography of Ca2+-saturated CAM–melittin complexes and molecular dynamics simulations\",\n      \"pmids\": [\"36906144\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Melittin is a model peptide, not a physiological CAM target\", \"Conformational ensemble not confirmed for native effectors like PfPKB\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Placed CAM in a calcium-signaling complex with the calcium-dependent phosphatase PP7 and CDPK1 that governs early ring-stage development.\",\n      \"evidence\": \"Conditional DiCre disruption, phosphoproteomics, Co-IP/mass spectrometry, and in vitro phosphatase assay\",\n      \"pmids\": [\"39387582\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct CAM–PP7 binding interface not mapped\", \"CAM's specific contribution to the phenotype not isolated from PP7/CDPK1\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Proposed CAM as a candidate myosin regulatory light chain by showing it binds the MyoB IQ2 motif in vitro.\",\n      \"evidence\": \"In vitro pulldown/binding assay with four putative regulatory light chains\",\n      \"pmids\": [\"36273584\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Single in vitro pulldown with no CAM-specific functional follow-up\", \"In vivo role of CAM as a MyoB light chain unestablished\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Predicted CAM as a regulatory light chain for the processive class XXII myosin PfMyoF in perinuclear membrane trafficking.\",\n      \"evidence\": \"Structural prediction of up to six CAM copies binding the PfMyoF neck plus biochemical MyoF motor characterization\",\n      \"pmids\": [\"42141018\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"CAM–MyoF binding is a structural prediction without direct biochemical confirmation\", \"Functional consequence of CAM binding for MyoF activity untested\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"It remains unknown whether CAM is genetically essential and how its distinct effector arms (kinases, phosphatases, myosin light-chain roles) are prioritized during invasion versus ring-stage development, since almost all functional evidence rests on pharmacological inhibition or overexpression rather than clean loss-of-function.\",\n      \"evidence\": \"No direct CAM knockout/conditional-knockdown phenotype in the timeline\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No CAM-specific gene disruption phenotype reported\", \"Relative in vivo importance of each effector not quantified\", \"Physiological CAM target peptides not structurally resolved\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0005509\", \"supporting_discovery_ids\": [9, 15, 11]},\n      {\"term_id\": \"GO:0004683\", \"supporting_discovery_ids\": [7, 8, 16]},\n      {\"term_id\": \"GO:0019855\", \"supporting_discovery_ids\": [7]},\n      {\"term_id\": \"GO:0008179\", \"supporting_discovery_ids\": [5, 12]},\n      {\"term_id\": \"GO:0017022\", \"supporting_discovery_ids\": [13, 14]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005737\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"GO:0020009\", \"supporting_discovery_ids\": [0, 1, 16]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0019725\", \"supporting_discovery_ids\": [9, 15]},\n      {\"term_id\": \"GO:0019064\", \"supporting_discovery_ids\": [1, 8]},\n      {\"term_id\": \"GO:0007204\", \"supporting_discovery_ids\": [7, 15]}\n    ],\n    \"complexes\": [\n      \"CAM–PfPKB complex\",\n      \"CAM–calcineurin (PP2B) complex\",\n      \"CAM–PP7–CDPK1 calcium-signaling complex\"\n    ],\n    \"partners\": [\n      \"PfPKB (protein kinase B)\",\n      \"Calcineurin / PP2B\",\n      \"PP7 (serine/threonine phosphatase)\",\n      \"CDPK1 (via PP7 complex)\",\n      \"PfPK2 (CaMK homolog)\",\n      \"Myosin B (MyoB, IQ2 motif)\",\n      \"PfMyoF (predicted)\"\n    ],\n    \"other_free_text\": [\n      \"Single-copy gene on chromosome 14 with a single intron; sequence highly homologous to eukaryotic calmodulins [#2, #3].\",\n      \"Stage-regulated expression peaking at trophozoite/schizont transition, controlled at transcriptional and mRNA-stability levels [#4].\",\n      \"Promoter activity depends on poly(dA)·poly(dT) tracts and nuclear factor binding within the 5' flanking region [#6].\",\n      \"Ca2+-saturated CAM recognizes target peptides via an ensemble of conformers lacking classical anchoring, with a more thermally stable C-terminal domain than human CaM [#10, #11].\",\n      \"Not a selective antimalarial drug target owing to close similarity to human calmodulin [#10]; CAM sequence unchanged between chloroquine-resistant and -sensitive isolates [#3].\"\n    ]\n  }\n}","audit_flag":null,"strains":[{"strain":"Pf3D7","gene_id":"PF3D7_1434200","name":null,"product":"calmodulin","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PbANKA","gene_id":"PBANKA_1010600","name":null,"product":"calmodulin, putative","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PkH","gene_id":"PKNH_0420800","name":null,"product":"calmodulin, putative","uniprot_acc":null,"chromosome":null,"start_pos":null}],"gene_symbol":"CAM","evaluation":null}