{"gene":"PF3D7_0728000","run_date":"2026-09-08T12:51:27","timeline":{"discoveries":[{"year":2009,"finding":"PfeIK1 (eIK1) phosphorylates P. falciparum eIF2alpha in vitro, and eIF2alpha phosphorylation in response to amino acid starvation is abolished in pfeik1-knockout asexual parasites, establishing PfeIK1 as the kinase responsible for starvation-induced eIF2alpha phosphorylation.","method":"In vitro kinase assay with recombinant PfeIK1 and recombinant PfeIF2alpha; reverse genetics (gene disruption of pfeik1) with phenotypic readout of eIF2alpha phosphorylation under starvation","journal":"Malaria journal","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — direct in vitro phosphorylation of eIF2alpha substrate by PfeIK1, corroborated by genetic knockout showing loss of starvation-induced phosphorylation in vivo, two orthogonal methods in one study","pmids":["19435497"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2010,"finding":"The eIF2alpha kinase IK2 phosphorylates eIF2alpha in salivary gland sporozoites, leading to translation inhibition and accumulation of stalled mRNAs into granules; IK2 knockout sporozoites lack phosphorylated eIF2alpha and transform prematurely into liver stages, losing infectivity. An eIF2alpha phosphatase reverses this phosphorylation upon host injection.","method":"Genetic knockout of IK2; immunodetection of phosphorylated eIF2alpha; microscopic analysis of mRNA granules; sporozoite infectivity assays","journal":"The Journal of experimental medicine","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal genetic and biochemical evidence (KO + phosphorylation readout + functional infectivity phenotype), replicated across mosquito and mammalian host contexts","pmids":["20584882"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2012,"finding":"The kinase PK4 phosphorylates the regulatory serine 59 of P. falciparum eIF2alpha; this phosphorylation is essential for the completion of the erythrocytic cycle, arresting global protein synthesis in schizonts and gametocytes.","method":"Genetic knockout of PK4 with loss-of-function developmental phenotype; site-specific mutagenesis identifying serine 59 as the phosphorylation site; protein synthesis assays","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — site-specific residue identification (Ser59), genetic KO with defined developmental phenotype, and protein synthesis assay, multiple orthogonal methods in one study","pmids":["22355110"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2012,"finding":"Isoleucine starvation of intraerythrocytic P. falciparum results in GCN2 (eIK1)-mediated phosphorylation of eIF2alpha; however, GCN2 kinase-knockout clones can still hibernate and recover, indicating that the eIF2alpha phosphorylation pathway does not directly promote survival during isoleucine starvation.","method":"Kinase-knockout clones; parasite viability and re-growth assays after isoleucine withdrawal; phosphorylation assays","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic KO with phenotypic readout, but the mechanistic conclusion is a negative result (eIF2alpha pathway not required for hibernation survival); single lab","pmids":["23112171"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2016,"finding":"UIS2, a PP2C/PPM-family phosphatase, dephosphorylates eIF2alpha phosphoserine-59 in Plasmodium sporozoites; conditional knockout of uis2 leads to high eIF2alpha phosphorylation, crescent-shaped sporozoites that fail to transform in the mammalian host, and loss of infectivity. UIS2 stably binds phosphorylated eIF2alpha, unlike the transient interactions of most eukaryotic phosphatases.","method":"Conditional genetic knockout of uis2; immunodetection of phosphorylated eIF2alpha; sporozoite morphology and infectivity assays; co-immunoprecipitation/binding assay of UIS2 with phosphorylated eIF2alpha","journal":"PLoS pathogens","confidence":"High","confidence_rationale":"Tier 2 / Moderate — genetic KO with clear phosphorylation and infectivity readouts, direct binding assay of UIS2 to phospho-eIF2alpha, multiple orthogonal methods in one study","pmids":["26735921"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2017,"finding":"Artemisinin treatment causes phosphorylation of eIF2alpha in P. falciparum, mediated by the kinase PK4, leading to global translation repression and latency induction; inhibiting PK4 (dominant-negative overexpression or pharmacological inhibition) blocks eIF2alpha phosphorylation, prevents parasite entry into latency, and abolishes recrudescence after artemisinin treatment in mice.","method":"PK4 dominant-negative overexpression; pharmacological PK4 inhibition; immunodetection of phosphorylated eIF2alpha; in vivo mouse infection recrudescence assays","journal":"Cell host & microbe","confidence":"High","confidence_rationale":"Tier 2 / Moderate — genetic and pharmacological perturbation of PK4, direct eIF2alpha phosphorylation readout, in vivo recrudescence assay, two orthogonal inhibition approaches","pmids":["29241041"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2006,"finding":"15-Deoxyspergualin induces phosphorylation of eIF2alpha in P. falciparum through Hsp70 sequestration, resulting in stalled protein synthesis; however, this eIF2alpha-mediated protein synthesis inhibition occurs only at high micromolar concentrations, whereas the primary antimalarial mechanism is via apicoplast protein trafficking inhibition at submicromolar concentrations.","method":"Protein synthesis assays; immunodetection of phosphorylated eIF2alpha; drug dose-response experiments","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 3 / Weak — phosphorylation of eIF2alpha detected by immunoassay under drug treatment, single method for the eIF2alpha finding, single lab","pmids":["17194705"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2016,"finding":"Addition of biliverdin to P. falciparum cultures alters the phosphorylation pattern of eIF2alpha, suggesting biliverdin-induced stress activates eIF2alpha kinases.","method":"Immunodetection of phosphorylated eIF2alpha in drug-treated parasite cultures","journal":"Scientific reports","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single immunodetection method, no kinase identified, single lab, no mechanistic follow-up on eIF2alpha specifically","pmids":["26915471"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2016,"finding":"Phosphorylation of eIF2alpha and attenuation of global protein synthesis occur during in vitro differentiation of P. berghei gametocytes to ookinetes under mosquito midgut-like oxidative stress conditions.","method":"Immunodetection of phosphorylated eIF2alpha; protein synthesis attenuation assay; reactive oxygen species detection; in vitro gametocyte-to-ookinete differentiation","journal":"Biochemistry and cell biology","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single immunodetection method under in vitro conditions, no kinase identified for eIF2alpha phosphorylation, single lab","pmids":["28177775"],"is_preprint":false,"attribution":[{"species":"Plasmodium berghei","strain":""}]},{"year":2019,"finding":"Loss of function of the ER chaperone PfGRP170 activates the P. falciparum eIF2alpha kinase PK4, indicating that PfGRP170 normally suppresses PK4-mediated eIF2alpha phosphorylation as part of the ER stress response pathway.","method":"Conditional mutant generation; immunodetection of PK4 activation downstream of PfGRP170 loss; co-immunoprecipitation of PfGRP170 with BiP","journal":"Cellular microbiology","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — conditional KO with downstream eIF2alpha kinase activation readout, places eIF2alpha in an ER stress pathway, single lab with genetic and biochemical methods","pmids":["31087747"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2019,"finding":"Halofuginone treatment induces eIF2alpha phosphorylation in P. falciparum; however, the adaptive proline response (APR) caused by halofuginone is independent of PfeIK1 and eIF2alpha signaling, as demonstrated by a pfeik1-knockout parasite line showing unaltered APR.","method":"Immunodetection of phosphorylated eIF2alpha; pfeik1-knockout parasites; drug tolerance (APR) assay","journal":"ACS infectious diseases","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic KO with two phenotypic readouts (eIF2alpha phosphorylation and APR), but the main finding is negative (eIF2alpha signaling not required for APR), single lab","pmids":["30773881"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2023,"finding":"P. falciparum eIK1 and eIK2 (eIF2alpha kinases) are critical for sensing and responding to distinct amino acid-limiting conditions across the life cycle, as shown by phenotypic screening of kinase-knockout mutants under amino acid deprivation; this sensing pathway is temporally regulated at distinct life cycle stages.","method":"Kinase-knockout mutant phenotypic screen; amino acid deprivation assays; life cycle stage analysis","journal":"Communications biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic KO screen with specific phenotypic readouts under defined AA-limiting conditions, but the direct eIF2alpha phosphorylation measurements are not described in detail in the abstract","pmids":["36810637"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2023,"finding":"Inhibition of P. falciparum glutamine synthetase (GS) reduces asparagine levels and induces eIF2alpha phosphorylation, leading to inhibition of protein synthesis and parasite death.","method":"GS inhibitor treatment (MSO, PPT); immunodetection of phosphorylated eIF2alpha; protein synthesis assay","journal":"Nature communications","confidence":"Low","confidence_rationale":"Tier 3 / Weak — eIF2alpha phosphorylation detected as downstream readout of GS inhibition, indirect pathway placement, single lab","pmids":["37452051"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2023,"finding":"P. falciparum cyclophilin 19B (PfCYP19B) acts as a negative regulator of the integrated stress response by modulating levels of phosphorylated eIF2alpha; overexpression of PfCYP19B reduces eIF2alpha-P and contributes to artemisinin resistance.","method":"Overexpression of PfCYP19B; immunodetection of phosphorylated eIF2alpha; drug resistance assays","journal":"PLoS pathogens","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — gain-of-function with direct eIF2alpha phosphorylation readout and functional drug resistance phenotype, single lab, mechanism of PfCYP19B action on eIF2alpha kinase/phosphatase not resolved","pmids":["36696458"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2025,"finding":"The phosphatase UIS2 binds eIF2alpha phosphoserine-59 through its N-terminal and phosphatase domains via electrostatic interactions; integrated structural modeling (AlphaFold + molecular dynamics) defines a binding pocket in the phosphatase domain distinct from human PP1α, with six cooperative binding patches. Salubrinal competes with the phospho-eIF2alpha peptide for this pocket via hydrophobic and hydrogen-bonding interactions at three of these patches.","method":"Integrated structural modeling (AlphaFold, molecular dynamics, metadynamics simulations); molecular docking; free energy perturbation analysis; domain-binding assays","journal":"bioRxiv","confidence":"Low","confidence_rationale":"Tier 4 / Weak — primarily computational modeling without experimental in vitro or in vivo structural validation reported in the abstract; preprint","pmids":["40463039"],"is_preprint":true,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2025,"finding":"The phosphatase PfPPM2 represses eIF2alpha phosphorylation in P. falciparum, thereby regulating protein synthesis; loss of PfPPM2 function increases eIF2alpha phosphorylation and affects parasite asexual division and sexual conversion.","method":"Conditional loss-of-function of PfPPM2; immunodetection of phosphorylated eIF2alpha; parasite growth and gametocyte conversion assays","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — genetic perturbation with direct eIF2alpha phosphorylation readout and defined developmental phenotypes, single lab","pmids":["40410154"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]}],"current_model":"P. falciparum eIF2alpha (PF3D7_0728000) is a central translational regulator whose activity is controlled by phosphorylation at serine 59 (catalyzed by the kinases PK4, IK2/UIS1, and eIK1/GCN2 in a stage- and stress-specific manner) and dephosphorylation by the parasite-specific PP2C phosphatase UIS2 (and PfPPM2); phosphorylated eIF2alpha represses global protein synthesis, driving sporozoite latency in mosquito salivary glands, schizont/gametocyte arrest in the erythrocytic cycle, and artemisinin-induced latency, while eIF2alpha dephosphorylation is required for sporozoite-to-liver stage transformation and resumption of active replication."},"narrative":{"mechanistic_narrative":"PF3D7_0728000 (eIF2alpha) is the central translational regulator of Plasmodium whose phosphorylation state gates global protein synthesis across the parasite life cycle and under stress [PMID:22355110, PMID:26735921]. Its activity is controlled by phosphorylation of the regulatory serine 59, identified by site-specific mutagenesis as the residue modified by the kinase PK4; this modification arrests protein synthesis in schizonts and gametocytes and is essential for completion of the erythrocytic cycle [PMID:22355110]. Multiple stage- and stress-specific kinases converge on eIF2alpha: PfeIK1/GCN2 phosphorylates it in response to amino acid (isoleucine) starvation in asexual parasites [PMID:19435497, PMID:23112171], and IK2 phosphorylates it in salivary gland sporozoites to drive translational latency, stalling mRNAs into granules and maintaining sporozoite infectivity until host injection [PMID:20584882]. eIK1 and eIK2 respond to distinct amino acid-limiting conditions at temporally separated life cycle stages [PMID:36810637]. Reversal of this modification is carried out by the PP2C/PPM-family phosphatase UIS2, which dephosphorylates eIF2alpha phosphoserine-59 and, unusually for a eukaryotic phosphatase, stably binds the phosphorylated substrate; loss of UIS2 raises eIF2alpha phosphorylation and blocks sporozoite transformation in the host [PMID:26735921]. The phosphatase PfPPM2 similarly represses eIF2alpha phosphorylation and influences asexual division and sexual conversion [PMID:40410154]. Beyond its developmental roles, eIF2alpha phosphorylation is a node of drug response: PK4-mediated phosphorylation of eIF2alpha drives artemisinin-induced latency and recrudescence [PMID:29241041], and the pathway is engaged by ER stress via PfGRP170-restrained PK4 activation [PMID:31087747]. The direct molecular activity of eIF2alpha itself beyond serving as the serine-59 phosphoacceptor substrate has not been characterized in the available corpus.","teleology":[{"year":2009,"claim":"Establishing which kinase phosphorylates eIF2alpha under nutrient stress was needed to connect the initiation factor to a defined signaling input; PfeIK1 was identified as the kinase for starvation-induced phosphorylation.","evidence":"In vitro kinase assay with recombinant PfeIK1 and eIF2alpha, plus pfeik1 gene disruption abolishing starvation-induced phosphorylation","pmids":["19435497"],"confidence":"High","gaps":["Did not map the phosphorylated residue on eIF2alpha","Did not test whether other kinases redundantly phosphorylate eIF2alpha under starvation"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2010,"claim":"Whether eIF2alpha phosphorylation controls a discrete developmental transition was open; IK2-mediated phosphorylation was shown to enforce sporozoite translational latency and preserve infectivity, with a phosphatase reversing it on host entry.","evidence":"IK2 knockout with phospho-eIF2alpha immunodetection, mRNA granule microscopy, and sporozoite infectivity assays","pmids":["20584882"],"confidence":"High","gaps":["Identity of the reversing phosphatase not resolved in this study","Direct demonstration that IK2 phosphorylates eIF2alpha biochemically not shown"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2012,"claim":"The regulatory residue and the erythrocytic-cycle requirement were unknown; serine 59 was defined as the PK4 phosphorylation site required to arrest protein synthesis in schizonts and gametocytes.","evidence":"PK4 knockout with developmental phenotype, site-specific mutagenesis of serine 59, and protein synthesis assays","pmids":["22355110"],"confidence":"High","gaps":["Downstream mRNAs preferentially translated during arrest not identified","Interplay with other kinases at the same residue not delineated"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2012,"claim":"Whether the eIF2alpha phosphorylation pathway itself confers survival during isoleucine starvation was tested; GCN2/eIK1 knockouts still hibernated and recovered, dissociating survival from this pathway.","evidence":"GCN2 kinase-knockout clones with viability, re-growth, and phosphorylation assays after isoleucine withdrawal","pmids":["23112171"],"confidence":"Medium","gaps":["Negative result does not exclude a modulatory role","Alternative survival pathway not identified"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2016,"claim":"The phosphatase reversing eIF2alpha phosphorylation and its mode of substrate engagement were unknown; UIS2 was shown to dephosphorylate phosphoserine-59 and to bind the phosphorylated substrate stably, controlling sporozoite transformation.","evidence":"Conditional uis2 knockout, phospho-eIF2alpha immunodetection, sporozoite morphology/infectivity assays, and UIS2–phospho-eIF2alpha binding assay","pmids":["26735921"],"confidence":"High","gaps":["Structural basis of the stable interaction not resolved here","Whether UIS2 acts on eIF2alpha in blood stages not addressed"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2017,"claim":"The mechanism of artemisinin-induced latency was unclear; PK4-mediated eIF2alpha phosphorylation was shown to drive translational repression and recrudescence, blockable by PK4 inhibition.","evidence":"PK4 dominant-negative overexpression, pharmacological PK4 inhibition, phospho-eIF2alpha immunodetection, and in vivo mouse recrudescence assays","pmids":["29241041"],"confidence":"High","gaps":["How artemisinin activates PK4 upstream not defined","Reversal step out of drug-induced latency not characterized"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2019,"claim":"An ER-stress input to eIF2alpha phosphorylation was sought; loss of the ER chaperone PfGRP170 activates PK4, placing eIF2alpha downstream of a chaperone-restrained ER stress response.","evidence":"Conditional PfGRP170 mutant with PK4-activation readout and PfGRP170–BiP co-immunoprecipitation","pmids":["31087747"],"confidence":"Medium","gaps":["Direct effect on eIF2alpha phosphorylation levels quantified only indirectly","Mechanism linking GRP170 loss to PK4 activation unresolved"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2019,"claim":"Whether eIF2alpha signaling mediates the adaptive response to halofuginone-induced proline stress was tested; the adaptive proline response was shown to be independent of PfeIK1 and eIF2alpha, despite drug-induced phosphorylation.","evidence":"Phospho-eIF2alpha immunodetection and pfeik1-knockout drug-tolerance (APR) assay","pmids":["30773881"],"confidence":"Medium","gaps":["Negative result; other kinases driving the observed phosphorylation not identified","Functional consequence of the drug-induced phosphorylation unclear"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2023,"claim":"The division of labor among eIF2alpha kinases across the life cycle was refined; eIK1 and eIK2 were shown to sense distinct amino acid-limiting conditions at temporally separated stages.","evidence":"Kinase-knockout mutant phenotypic screen under defined amino acid deprivation with life cycle stage analysis","pmids":["36810637"],"confidence":"Medium","gaps":["Direct eIF2alpha phosphorylation measurements not detailed","How each kinase distinguishes specific amino acid limitations not defined"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2023,"claim":"Additional regulators of the eIF2alpha stress response were sought; PfCYP19B was shown to act as a negative regulator of phospho-eIF2alpha, contributing to artemisinin resistance.","evidence":"PfCYP19B overexpression with phospho-eIF2alpha immunodetection and drug resistance assays","pmids":["36696458"],"confidence":"Medium","gaps":["Whether PfCYP19B acts on a kinase or phosphatase unresolved","No direct interaction with eIF2alpha demonstrated"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2025,"claim":"A second phosphatase restraining eIF2alpha phosphorylation was identified; PfPPM2 represses eIF2alpha phosphorylation and influences asexual division and sexual conversion.","evidence":"Conditional PfPPM2 loss-of-function with phospho-eIF2alpha immunodetection and growth/gametocyte conversion assays","pmids":["40410154"],"confidence":"Medium","gaps":["Direct dephosphorylation of eIF2alpha by PfPPM2 in vitro not shown","Division of labor between PfPPM2 and UIS2 not resolved"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2025,"claim":"The structural basis of UIS2 recognition of phospho-eIF2alpha was modeled; a phosphatase-domain pocket distinct from human PP1alpha with cooperative binding patches was defined, and salubrinal was shown computationally to compete for it.","evidence":"Integrated structural modeling (AlphaFold, molecular dynamics, metadynamics), docking, free energy perturbation, and domain-binding analysis (preprint)","pmids":["40463039"],"confidence":"Low","gaps":["Primarily computational; no experimental structural validation reported","Predicted binding patches not tested by mutagenesis"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":null,"claim":"The intrinsic molecular activity of eIF2alpha within the initiation complex and the identity of mRNAs selectively regulated by its phosphorylation state remain undefined in this corpus.","evidence":"No timeline discovery characterizes eIF2alpha's role in ternary complex/GTPase function or its translational targets directly","pmids":[],"confidence":"Low","gaps":["No characterization of eIF2 ternary complex assembly for this protein","Selectively translated mRNAs during phospho-eIF2alpha arrest not mapped","Blood-stage phosphatase(s) versus sporozoite UIS2 roles not fully partitioned"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]}],"mechanism_profile":{"molecular_activity":[],"localization":[],"pathway":[],"complexes":[],"partners":["PK4 (KINASE, PHOSPHORYLATES EIF2ALPHA SER59) [#2, #5, #9]","IK2 (KINASE, PHOSPHORYLATES EIF2ALPHA IN SPOROZOITES) [#1]","PFEIK1/GCN2/EIK1 (KINASE, STARVATION-INDUCED PHOSPHORYLATION) [#0, #3, #11]","EIK2 (KINASE, AMINO ACID SENSING) [#11]","UIS2 (PP2C/PPM PHOSPHATASE, DEPHOSPHORYLATES AND STABLY BINDS PHOSPHO-EIF2ALPHA SER59) [#4, #14]","PFPPM2 (PHOSPHATASE, REPRESSES EIF2ALPHA PHOSPHORYLATION) [#15]","PFCYP19B (NEGATIVE REGULATOR OF PHOSPHO-EIF2ALPHA) [#13]","PFGRP170 (ER CHAPERONE RESTRAINING PK4 ACTIVATION UPSTREAM) [#9]"],"other_free_text":["Regulatory phosphosite mapped to serine 59 [#2].","Phosphorylation drives sporozoite latency and gates transformation to liver stage [#1, #4].","Phosphorylation enforces schizont/gametocyte protein synthesis arrest and erythrocytic cycle completion [#2].","PK4-mediated eIF2alpha phosphorylation underlies artemisinin-induced latency and recrudescence [#5].","eIF2alpha phosphorylation is dispensable for isoleucine-starvation survival and for the halofuginone adaptive proline response [#3, #10].","In P. berghei, eIF2alpha phosphorylation accompanies gametocyte-to-ookinete differentiation under oxidative stress [#8].","Drug-induced eIF2alpha phosphorylation observed with 15-deoxyspergualin (Hsp70 sequestration), biliverdin, and glutamine synthetase inhibition [#6, #7, #12]."]}},"prefetch_data":{},"corpus_meta":[{"pmid":"23112171","id":"PMC_23112171","title":"Plasmodium falciparum responds to amino acid starvation by entering into a hibernatory state.","date":"2012","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/23112171","citation_count":125,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["eIF2alpha"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"20584882","id":"PMC_20584882","title":"The Plasmodium eukaryotic initiation factor-2alpha kinase IK2 controls the latency of sporozoites in the mosquito salivary glands.","date":"2010","source":"The Journal of experimental medicine","url":"https://pubmed.ncbi.nlm.nih.gov/20584882","citation_count":109,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["eIF2alpha"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"29241041","id":"PMC_29241041","title":"Inhibiting the Plasmodium eIF2α Kinase PK4 Prevents Artemisinin-Induced Latency.","date":"2017","source":"Cell host & microbe","url":"https://pubmed.ncbi.nlm.nih.gov/29241041","citation_count":105,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["eIF2alpha"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"22355110","id":"PMC_22355110","title":"PK4, a eukaryotic initiation factor 2α(eIF2α) kinase, is essential for the development of the erythrocytic cycle of Plasmodium.","date":"2012","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/22355110","citation_count":80,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["eIF2alpha"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"26955948","id":"PMC_26955948","title":"Plasmodium falciparum: multifaceted resistance to artemisinins.","date":"2016","source":"Malaria 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journal","url":"https://pubmed.ncbi.nlm.nih.gov/9371731","citation_count":47,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["eIF2alpha"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"26735921","id":"PMC_26735921","title":"UIS2: A Unique Phosphatase Required for the Development of Plasmodium Liver Stages.","date":"2016","source":"PLoS pathogens","url":"https://pubmed.ncbi.nlm.nih.gov/26735921","citation_count":38,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["eIF2alpha"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"17194705","id":"PMC_17194705","title":"15-deoxyspergualin primarily targets the trafficking of apicoplast proteins in Plasmodium falciparum.","date":"2006","source":"The Journal of biological 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falciparum.","date":"2016","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/26915471","citation_count":15,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["eIF2alpha"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"36810637","id":"PMC_36810637","title":"A non-canonical sensing pathway mediates Plasmodium adaptation to amino acid deficiency.","date":"2023","source":"Communications biology","url":"https://pubmed.ncbi.nlm.nih.gov/36810637","citation_count":13,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["eIF2alpha"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"30773881","id":"PMC_30773881","title":"The Adaptive Proline Response in P. falciparum Is Independent of PfeIK1 and eIF2α Signaling.","date":"2019","source":"ACS infectious diseases","url":"https://pubmed.ncbi.nlm.nih.gov/30773881","citation_count":12,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["eIF2alpha"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"28357358","id":"PMC_28357358","title":"Translational Repression in Malaria Sporozoites.","date":"2016","source":"Microbial cell (Graz, Austria)","url":"https://pubmed.ncbi.nlm.nih.gov/28357358","citation_count":8,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["eIF2alpha"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"28177775","id":"PMC_28177775","title":"Cellular stress associated with the differentiation of Plasmodium berghei ookinetes.","date":"2016","source":"Biochemistry and cell biology = Biochimie et biologie cellulaire","url":"https://pubmed.ncbi.nlm.nih.gov/28177775","citation_count":8,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["eIF2alpha"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"36696458","id":"PMC_36696458","title":"Short tandem repeat polymorphism in the promoter region of cyclophilin 19B drives its transcriptional upregulation and contributes to drug resistance in the malaria parasite Plasmodium falciparum.","date":"2023","source":"PLoS pathogens","url":"https://pubmed.ncbi.nlm.nih.gov/36696458","citation_count":7,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["eIF2alpha"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"37452051","id":"PMC_37452051","title":"Distinct evolution of type I glutamine synthetase in Plasmodium and its species-specific requirement.","date":"2023","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/37452051","citation_count":6,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["eIF2alpha"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"40410154","id":"PMC_40410154","title":"PfPPM2 signalling regulates asexual division and sexual conversion of human malaria parasite Plasmodium falciparum.","date":"2025","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/40410154","citation_count":2,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["eIF2alpha"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"36375338","id":"PMC_36375338","title":"Anti-malarial activity of HCl salt of SKM13 (SKM13-2HCl).","date":"2022","source":"International journal for parasitology. Drugs and drug resistance","url":"https://pubmed.ncbi.nlm.nih.gov/36375338","citation_count":2,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["eIF2alpha"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"40463039","id":"PMC_40463039","title":"Mechanistic Insights into the Plasmodium Phosphatase UIS2 in eIF2α Dephosphorylation via Integrated Structure-Based Modeling.","date":"2025","source":"bioRxiv : the preprint server for biology","url":"https://pubmed.ncbi.nlm.nih.gov/40463039","citation_count":0,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["eIF2alpha"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"29241036","id":"PMC_29241036","title":"Plasmodium Peekaboo: PK4 Mediates Parasite Latency.","date":"2017","source":"Cell host & microbe","url":"https://pubmed.ncbi.nlm.nih.gov/29241036","citation_count":0,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["eIF2alpha"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"41286015","id":"PMC_41286015","title":"PfPI3K inhibition reversed artemisinin resistance by increasing ROS and ubiquitinated protein levels in Plasmodium falciparum.","date":"2025","source":"Communications biology","url":"https://pubmed.ncbi.nlm.nih.gov/41286015","citation_count":0,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["eIF2alpha"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":13436,"output_tokens":4480,"usd":0.053754,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":10921,"output_tokens":5213,"usd":0.092465,"stage2_stop_reason":"end_turn"},"total_usd":0.146219,"stage1_batch_id":"msgbatch_01DisAaTypwmC8QwdMBuePHo","stage2_batch_id":"msgbatch_0184zxZTqxiEfdYYfPMfkqjb","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2009,\n      \"finding\": \"PfeIK1 (eIK1) phosphorylates P. falciparum eIF2alpha in vitro, and eIF2alpha phosphorylation in response to amino acid starvation is abolished in pfeik1-knockout asexual parasites, establishing PfeIK1 as the kinase responsible for starvation-induced eIF2alpha phosphorylation.\",\n      \"method\": \"In vitro kinase assay with recombinant PfeIK1 and recombinant PfeIF2alpha; reverse genetics (gene disruption of pfeik1) with phenotypic readout of eIF2alpha phosphorylation under starvation\",\n      \"journal\": \"Malaria journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — direct in vitro phosphorylation of eIF2alpha substrate by PfeIK1, corroborated by genetic knockout showing loss of starvation-induced phosphorylation in vivo, two orthogonal methods in one study\",\n      \"pmids\": [\"19435497\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"The eIF2alpha kinase IK2 phosphorylates eIF2alpha in salivary gland sporozoites, leading to translation inhibition and accumulation of stalled mRNAs into granules; IK2 knockout sporozoites lack phosphorylated eIF2alpha and transform prematurely into liver stages, losing infectivity. An eIF2alpha phosphatase reverses this phosphorylation upon host injection.\",\n      \"method\": \"Genetic knockout of IK2; immunodetection of phosphorylated eIF2alpha; microscopic analysis of mRNA granules; sporozoite infectivity assays\",\n      \"journal\": \"The Journal of experimental medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal genetic and biochemical evidence (KO + phosphorylation readout + functional infectivity phenotype), replicated across mosquito and mammalian host contexts\",\n      \"pmids\": [\"20584882\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"The kinase PK4 phosphorylates the regulatory serine 59 of P. falciparum eIF2alpha; this phosphorylation is essential for the completion of the erythrocytic cycle, arresting global protein synthesis in schizonts and gametocytes.\",\n      \"method\": \"Genetic knockout of PK4 with loss-of-function developmental phenotype; site-specific mutagenesis identifying serine 59 as the phosphorylation site; protein synthesis assays\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — site-specific residue identification (Ser59), genetic KO with defined developmental phenotype, and protein synthesis assay, multiple orthogonal methods in one study\",\n      \"pmids\": [\"22355110\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Isoleucine starvation of intraerythrocytic P. falciparum results in GCN2 (eIK1)-mediated phosphorylation of eIF2alpha; however, GCN2 kinase-knockout clones can still hibernate and recover, indicating that the eIF2alpha phosphorylation pathway does not directly promote survival during isoleucine starvation.\",\n      \"method\": \"Kinase-knockout clones; parasite viability and re-growth assays after isoleucine withdrawal; phosphorylation assays\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic KO with phenotypic readout, but the mechanistic conclusion is a negative result (eIF2alpha pathway not required for hibernation survival); single lab\",\n      \"pmids\": [\"23112171\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"UIS2, a PP2C/PPM-family phosphatase, dephosphorylates eIF2alpha phosphoserine-59 in Plasmodium sporozoites; conditional knockout of uis2 leads to high eIF2alpha phosphorylation, crescent-shaped sporozoites that fail to transform in the mammalian host, and loss of infectivity. UIS2 stably binds phosphorylated eIF2alpha, unlike the transient interactions of most eukaryotic phosphatases.\",\n      \"method\": \"Conditional genetic knockout of uis2; immunodetection of phosphorylated eIF2alpha; sporozoite morphology and infectivity assays; co-immunoprecipitation/binding assay of UIS2 with phosphorylated eIF2alpha\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic KO with clear phosphorylation and infectivity readouts, direct binding assay of UIS2 to phospho-eIF2alpha, multiple orthogonal methods in one study\",\n      \"pmids\": [\"26735921\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Artemisinin treatment causes phosphorylation of eIF2alpha in P. falciparum, mediated by the kinase PK4, leading to global translation repression and latency induction; inhibiting PK4 (dominant-negative overexpression or pharmacological inhibition) blocks eIF2alpha phosphorylation, prevents parasite entry into latency, and abolishes recrudescence after artemisinin treatment in mice.\",\n      \"method\": \"PK4 dominant-negative overexpression; pharmacological PK4 inhibition; immunodetection of phosphorylated eIF2alpha; in vivo mouse infection recrudescence assays\",\n      \"journal\": \"Cell host & microbe\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic and pharmacological perturbation of PK4, direct eIF2alpha phosphorylation readout, in vivo recrudescence assay, two orthogonal inhibition approaches\",\n      \"pmids\": [\"29241041\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"15-Deoxyspergualin induces phosphorylation of eIF2alpha in P. falciparum through Hsp70 sequestration, resulting in stalled protein synthesis; however, this eIF2alpha-mediated protein synthesis inhibition occurs only at high micromolar concentrations, whereas the primary antimalarial mechanism is via apicoplast protein trafficking inhibition at submicromolar concentrations.\",\n      \"method\": \"Protein synthesis assays; immunodetection of phosphorylated eIF2alpha; drug dose-response experiments\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Weak — phosphorylation of eIF2alpha detected by immunoassay under drug treatment, single method for the eIF2alpha finding, single lab\",\n      \"pmids\": [\"17194705\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Addition of biliverdin to P. falciparum cultures alters the phosphorylation pattern of eIF2alpha, suggesting biliverdin-induced stress activates eIF2alpha kinases.\",\n      \"method\": \"Immunodetection of phosphorylated eIF2alpha in drug-treated parasite cultures\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single immunodetection method, no kinase identified, single lab, no mechanistic follow-up on eIF2alpha specifically\",\n      \"pmids\": [\"26915471\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Phosphorylation of eIF2alpha and attenuation of global protein synthesis occur during in vitro differentiation of P. berghei gametocytes to ookinetes under mosquito midgut-like oxidative stress conditions.\",\n      \"method\": \"Immunodetection of phosphorylated eIF2alpha; protein synthesis attenuation assay; reactive oxygen species detection; in vitro gametocyte-to-ookinete differentiation\",\n      \"journal\": \"Biochemistry and cell biology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single immunodetection method under in vitro conditions, no kinase identified for eIF2alpha phosphorylation, single lab\",\n      \"pmids\": [\"28177775\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium berghei\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Loss of function of the ER chaperone PfGRP170 activates the P. falciparum eIF2alpha kinase PK4, indicating that PfGRP170 normally suppresses PK4-mediated eIF2alpha phosphorylation as part of the ER stress response pathway.\",\n      \"method\": \"Conditional mutant generation; immunodetection of PK4 activation downstream of PfGRP170 loss; co-immunoprecipitation of PfGRP170 with BiP\",\n      \"journal\": \"Cellular microbiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — conditional KO with downstream eIF2alpha kinase activation readout, places eIF2alpha in an ER stress pathway, single lab with genetic and biochemical methods\",\n      \"pmids\": [\"31087747\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Halofuginone treatment induces eIF2alpha phosphorylation in P. falciparum; however, the adaptive proline response (APR) caused by halofuginone is independent of PfeIK1 and eIF2alpha signaling, as demonstrated by a pfeik1-knockout parasite line showing unaltered APR.\",\n      \"method\": \"Immunodetection of phosphorylated eIF2alpha; pfeik1-knockout parasites; drug tolerance (APR) assay\",\n      \"journal\": \"ACS infectious diseases\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic KO with two phenotypic readouts (eIF2alpha phosphorylation and APR), but the main finding is negative (eIF2alpha signaling not required for APR), single lab\",\n      \"pmids\": [\"30773881\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"P. falciparum eIK1 and eIK2 (eIF2alpha kinases) are critical for sensing and responding to distinct amino acid-limiting conditions across the life cycle, as shown by phenotypic screening of kinase-knockout mutants under amino acid deprivation; this sensing pathway is temporally regulated at distinct life cycle stages.\",\n      \"method\": \"Kinase-knockout mutant phenotypic screen; amino acid deprivation assays; life cycle stage analysis\",\n      \"journal\": \"Communications biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic KO screen with specific phenotypic readouts under defined AA-limiting conditions, but the direct eIF2alpha phosphorylation measurements are not described in detail in the abstract\",\n      \"pmids\": [\"36810637\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Inhibition of P. falciparum glutamine synthetase (GS) reduces asparagine levels and induces eIF2alpha phosphorylation, leading to inhibition of protein synthesis and parasite death.\",\n      \"method\": \"GS inhibitor treatment (MSO, PPT); immunodetection of phosphorylated eIF2alpha; protein synthesis assay\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — eIF2alpha phosphorylation detected as downstream readout of GS inhibition, indirect pathway placement, single lab\",\n      \"pmids\": [\"37452051\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"P. falciparum cyclophilin 19B (PfCYP19B) acts as a negative regulator of the integrated stress response by modulating levels of phosphorylated eIF2alpha; overexpression of PfCYP19B reduces eIF2alpha-P and contributes to artemisinin resistance.\",\n      \"method\": \"Overexpression of PfCYP19B; immunodetection of phosphorylated eIF2alpha; drug resistance assays\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — gain-of-function with direct eIF2alpha phosphorylation readout and functional drug resistance phenotype, single lab, mechanism of PfCYP19B action on eIF2alpha kinase/phosphatase not resolved\",\n      \"pmids\": [\"36696458\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"The phosphatase UIS2 binds eIF2alpha phosphoserine-59 through its N-terminal and phosphatase domains via electrostatic interactions; integrated structural modeling (AlphaFold + molecular dynamics) defines a binding pocket in the phosphatase domain distinct from human PP1α, with six cooperative binding patches. Salubrinal competes with the phospho-eIF2alpha peptide for this pocket via hydrophobic and hydrogen-bonding interactions at three of these patches.\",\n      \"method\": \"Integrated structural modeling (AlphaFold, molecular dynamics, metadynamics simulations); molecular docking; free energy perturbation analysis; domain-binding assays\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 4 / Weak — primarily computational modeling without experimental in vitro or in vivo structural validation reported in the abstract; preprint\",\n      \"pmids\": [\"40463039\"],\n      \"is_preprint\": true,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"The phosphatase PfPPM2 represses eIF2alpha phosphorylation in P. falciparum, thereby regulating protein synthesis; loss of PfPPM2 function increases eIF2alpha phosphorylation and affects parasite asexual division and sexual conversion.\",\n      \"method\": \"Conditional loss-of-function of PfPPM2; immunodetection of phosphorylated eIF2alpha; parasite growth and gametocyte conversion assays\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — genetic perturbation with direct eIF2alpha phosphorylation readout and defined developmental phenotypes, single lab\",\n      \"pmids\": [\"40410154\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    }\n  ],\n  \"current_model\": \"P. falciparum eIF2alpha (PF3D7_0728000) is a central translational regulator whose activity is controlled by phosphorylation at serine 59 (catalyzed by the kinases PK4, IK2/UIS1, and eIK1/GCN2 in a stage- and stress-specific manner) and dephosphorylation by the parasite-specific PP2C phosphatase UIS2 (and PfPPM2); phosphorylated eIF2alpha represses global protein synthesis, driving sporozoite latency in mosquito salivary glands, schizont/gametocyte arrest in the erythrocytic cycle, and artemisinin-induced latency, while eIF2alpha dephosphorylation is required for sporozoite-to-liver stage transformation and resumption of active replication.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"PF3D7_0728000 (eIF2alpha) is the central translational regulator of Plasmodium whose phosphorylation state gates global protein synthesis across the parasite life cycle and under stress [#2, #4]. Its activity is controlled by phosphorylation of the regulatory serine 59, identified by site-specific mutagenesis as the residue modified by the kinase PK4; this modification arrests protein synthesis in schizonts and gametocytes and is essential for completion of the erythrocytic cycle [#2]. Multiple stage- and stress-specific kinases converge on eIF2alpha: PfeIK1/GCN2 phosphorylates it in response to amino acid (isoleucine) starvation in asexual parasites [#0, #3], and IK2 phosphorylates it in salivary gland sporozoites to drive translational latency, stalling mRNAs into granules and maintaining sporozoite infectivity until host injection [#1]. eIK1 and eIK2 respond to distinct amino acid-limiting conditions at temporally separated life cycle stages [#11]. Reversal of this modification is carried out by the PP2C/PPM-family phosphatase UIS2, which dephosphorylates eIF2alpha phosphoserine-59 and, unusually for a eukaryotic phosphatase, stably binds the phosphorylated substrate; loss of UIS2 raises eIF2alpha phosphorylation and blocks sporozoite transformation in the host [#4]. The phosphatase PfPPM2 similarly represses eIF2alpha phosphorylation and influences asexual division and sexual conversion [#15]. Beyond its developmental roles, eIF2alpha phosphorylation is a node of drug response: PK4-mediated phosphorylation of eIF2alpha drives artemisinin-induced latency and recrudescence [#5], and the pathway is engaged by ER stress via PfGRP170-restrained PK4 activation [#9]. The direct molecular activity of eIF2alpha itself beyond serving as the serine-59 phosphoacceptor substrate has not been characterized in the available corpus.\",\n  \"teleology\": [\n    {\n      \"year\": 2009,\n      \"claim\": \"Establishing which kinase phosphorylates eIF2alpha under nutrient stress was needed to connect the initiation factor to a defined signaling input; PfeIK1 was identified as the kinase for starvation-induced phosphorylation.\",\n      \"evidence\": \"In vitro kinase assay with recombinant PfeIK1 and eIF2alpha, plus pfeik1 gene disruption abolishing starvation-induced phosphorylation\",\n      \"pmids\": [\"19435497\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not map the phosphorylated residue on eIF2alpha\", \"Did not test whether other kinases redundantly phosphorylate eIF2alpha under starvation\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Whether eIF2alpha phosphorylation controls a discrete developmental transition was open; IK2-mediated phosphorylation was shown to enforce sporozoite translational latency and preserve infectivity, with a phosphatase reversing it on host entry.\",\n      \"evidence\": \"IK2 knockout with phospho-eIF2alpha immunodetection, mRNA granule microscopy, and sporozoite infectivity assays\",\n      \"pmids\": [\"20584882\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Identity of the reversing phosphatase not resolved in this study\", \"Direct demonstration that IK2 phosphorylates eIF2alpha biochemically not shown\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"The regulatory residue and the erythrocytic-cycle requirement were unknown; serine 59 was defined as the PK4 phosphorylation site required to arrest protein synthesis in schizonts and gametocytes.\",\n      \"evidence\": \"PK4 knockout with developmental phenotype, site-specific mutagenesis of serine 59, and protein synthesis assays\",\n      \"pmids\": [\"22355110\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Downstream mRNAs preferentially translated during arrest not identified\", \"Interplay with other kinases at the same residue not delineated\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Whether the eIF2alpha phosphorylation pathway itself confers survival during isoleucine starvation was tested; GCN2/eIK1 knockouts still hibernated and recovered, dissociating survival from this pathway.\",\n      \"evidence\": \"GCN2 kinase-knockout clones with viability, re-growth, and phosphorylation assays after isoleucine withdrawal\",\n      \"pmids\": [\"23112171\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Negative result does not exclude a modulatory role\", \"Alternative survival pathway not identified\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"The phosphatase reversing eIF2alpha phosphorylation and its mode of substrate engagement were unknown; UIS2 was shown to dephosphorylate phosphoserine-59 and to bind the phosphorylated substrate stably, controlling sporozoite transformation.\",\n      \"evidence\": \"Conditional uis2 knockout, phospho-eIF2alpha immunodetection, sporozoite morphology/infectivity assays, and UIS2–phospho-eIF2alpha binding assay\",\n      \"pmids\": [\"26735921\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of the stable interaction not resolved here\", \"Whether UIS2 acts on eIF2alpha in blood stages not addressed\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"The mechanism of artemisinin-induced latency was unclear; PK4-mediated eIF2alpha phosphorylation was shown to drive translational repression and recrudescence, blockable by PK4 inhibition.\",\n      \"evidence\": \"PK4 dominant-negative overexpression, pharmacological PK4 inhibition, phospho-eIF2alpha immunodetection, and in vivo mouse recrudescence assays\",\n      \"pmids\": [\"29241041\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How artemisinin activates PK4 upstream not defined\", \"Reversal step out of drug-induced latency not characterized\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"An ER-stress input to eIF2alpha phosphorylation was sought; loss of the ER chaperone PfGRP170 activates PK4, placing eIF2alpha downstream of a chaperone-restrained ER stress response.\",\n      \"evidence\": \"Conditional PfGRP170 mutant with PK4-activation readout and PfGRP170–BiP co-immunoprecipitation\",\n      \"pmids\": [\"31087747\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct effect on eIF2alpha phosphorylation levels quantified only indirectly\", \"Mechanism linking GRP170 loss to PK4 activation unresolved\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Whether eIF2alpha signaling mediates the adaptive response to halofuginone-induced proline stress was tested; the adaptive proline response was shown to be independent of PfeIK1 and eIF2alpha, despite drug-induced phosphorylation.\",\n      \"evidence\": \"Phospho-eIF2alpha immunodetection and pfeik1-knockout drug-tolerance (APR) assay\",\n      \"pmids\": [\"30773881\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Negative result; other kinases driving the observed phosphorylation not identified\", \"Functional consequence of the drug-induced phosphorylation unclear\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"The division of labor among eIF2alpha kinases across the life cycle was refined; eIK1 and eIK2 were shown to sense distinct amino acid-limiting conditions at temporally separated stages.\",\n      \"evidence\": \"Kinase-knockout mutant phenotypic screen under defined amino acid deprivation with life cycle stage analysis\",\n      \"pmids\": [\"36810637\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct eIF2alpha phosphorylation measurements not detailed\", \"How each kinase distinguishes specific amino acid limitations not defined\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Additional regulators of the eIF2alpha stress response were sought; PfCYP19B was shown to act as a negative regulator of phospho-eIF2alpha, contributing to artemisinin resistance.\",\n      \"evidence\": \"PfCYP19B overexpression with phospho-eIF2alpha immunodetection and drug resistance assays\",\n      \"pmids\": [\"36696458\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether PfCYP19B acts on a kinase or phosphatase unresolved\", \"No direct interaction with eIF2alpha demonstrated\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"A second phosphatase restraining eIF2alpha phosphorylation was identified; PfPPM2 represses eIF2alpha phosphorylation and influences asexual division and sexual conversion.\",\n      \"evidence\": \"Conditional PfPPM2 loss-of-function with phospho-eIF2alpha immunodetection and growth/gametocyte conversion assays\",\n      \"pmids\": [\"40410154\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct dephosphorylation of eIF2alpha by PfPPM2 in vitro not shown\", \"Division of labor between PfPPM2 and UIS2 not resolved\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"The structural basis of UIS2 recognition of phospho-eIF2alpha was modeled; a phosphatase-domain pocket distinct from human PP1alpha with cooperative binding patches was defined, and salubrinal was shown computationally to compete for it.\",\n      \"evidence\": \"Integrated structural modeling (AlphaFold, molecular dynamics, metadynamics), docking, free energy perturbation, and domain-binding analysis (preprint)\",\n      \"pmids\": [\"40463039\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Primarily computational; no experimental structural validation reported\", \"Predicted binding patches not tested by mutagenesis\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The intrinsic molecular activity of eIF2alpha within the initiation complex and the identity of mRNAs selectively regulated by its phosphorylation state remain undefined in this corpus.\",\n      \"evidence\": \"No timeline discovery characterizes eIF2alpha's role in ternary complex/GTPase function or its translational targets directly\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No characterization of eIF2 ternary complex assembly for this protein\", \"Selectively translated mRNAs during phospho-eIF2alpha arrest not mapped\", \"Blood-stage phosphatase(s) versus sporozoite UIS2 roles not fully partitioned\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0003743\", \"supporting_discovery_ids\": [2, 4]},\n      {\"term_id\": \"GO:0043022\", \"supporting_discovery_ids\": [4]}\n    ],\n    \"localization\": [],\n    \"pathway\": [\n      {\"term_id\": \"GO:0140467\", \"supporting_discovery_ids\": [9, 13]},\n      {\"term_id\": \"GO:0017148\", \"supporting_discovery_ids\": [1, 2, 5]},\n      {\"term_id\": \"GO:0006446\", \"supporting_discovery_ids\": [0, 2, 4, 15]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"PK4 (kinase, phosphorylates eIF2alpha Ser59) [#2, #5, #9]\",\n      \"IK2 (kinase, phosphorylates eIF2alpha in sporozoites) [#1]\",\n      \"PfeIK1/GCN2/eIK1 (kinase, starvation-induced phosphorylation) [#0, #3, #11]\",\n      \"eIK2 (kinase, amino acid sensing) [#11]\",\n      \"UIS2 (PP2C/PPM phosphatase, dephosphorylates and stably binds phospho-eIF2alpha Ser59) [#4, #14]\",\n      \"PfPPM2 (phosphatase, represses eIF2alpha phosphorylation) [#15]\",\n      \"PfCYP19B (negative regulator of phospho-eIF2alpha) [#13]\",\n      \"PfGRP170 (ER chaperone restraining PK4 activation upstream) [#9]\"\n    ],\n    \"other_free_text\": [\n      \"Regulatory phosphosite mapped to serine 59 [#2].\",\n      \"Phosphorylation drives sporozoite latency and gates transformation to liver stage [#1, #4].\",\n      \"Phosphorylation enforces schizont/gametocyte protein synthesis arrest and erythrocytic cycle completion [#2].\",\n      \"PK4-mediated eIF2alpha phosphorylation underlies artemisinin-induced latency and recrudescence [#5].\",\n      \"eIF2alpha phosphorylation is dispensable for isoleucine-starvation survival and for the halofuginone adaptive proline response [#3, #10].\",\n      \"In P. berghei, eIF2alpha phosphorylation accompanies gametocyte-to-ookinete differentiation under oxidative stress [#8].\",\n      \"Drug-induced eIF2alpha phosphorylation observed with 15-deoxyspergualin (Hsp70 sequestration), biliverdin, and glutamine synthetase inhibition [#6, #7, #12].\"\n    ]\n  }\n}","audit_flag":null,"strains":[{"strain":"Pf3D7","gene_id":"PF3D7_0728000","name":null,"product":"eukaryotic translation initiation factor 2 subunit alpha","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PbANKA","gene_id":"PBANKA_0212100","name":null,"product":"eukaryotic translation initiation factor 2 subunit alpha","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PkH","gene_id":"PKNH_0212600","name":null,"product":"eukaryotic translation initiation factor 2 subunit alpha, putative","uniprot_acc":null,"chromosome":null,"start_pos":null}],"gene_symbol":"eIF2alpha","evaluation":null}