{"gene":"PF3D7_1138500","run_date":"2026-09-08T19:44:17","timeline":{"discoveries":[{"year":1998,"finding":"PPM2 (PF3D7_1138500) encodes an unusually large (~920 aa) PP2C-family phosphatase in P. falciparum that contains two complete catalytic halves (Pf2C-1 and Pf2C-2), each possessing independent Mg2+/Mn2+-dependent serine/threonine phosphatase activity as demonstrated by dephosphorylation of 32P-labeled casein in vitro. Yeast two-hybrid and gel filtration of parasite extracts demonstrated that the two halves interact and that the full-length protein forms a dimer, and phosphatase competition experiments showed that dimerization is required for optimal activity. Each half alone can complement the heat-shock response defect of a S. pombe ptc1Δ mutant, as can the full-length protein or a chimeric construct.","method":"Recombinant protein phosphatase assay (32P-casein dephosphorylation), yeast two-hybrid, gel filtration, S. pombe complementation, site-directed domain dissection","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro enzymatic reconstitution with mutagenesis-level domain dissection, orthogonal yeast genetics (complementation + two-hybrid), and gel filtration all in one study","pmids":["9556615"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2025,"finding":"PPM2 (PF3D7_1138500) regulates both asexual division and sexual commitment in P. falciparum. Conditional depletion of PfPPM2 impairs asexual replication and reduces sexual conversion. Comparative phosphoproteomics after PfPPM2 depletion identified Heterochromatin Protein 1 (HP1) and translation initiation factor eIF2α as key targets: PfPPM2 directly dephosphorylates HP1 at serine 33, and this dephosphorylation promotes the interaction of HP1 with H3K9me3 and chromatin that is required for sexual commitment. PfPPM2 also represses eIF2α phosphorylation, thereby supporting protein synthesis during parasite division.","method":"Conditional knockdown (AID/auxin-inducible degron), quantitative phosphoproteomics, in vitro phosphatase assay (dephosphorylation of HP1-S33), chromatin immunoprecipitation, co-immunoprecipitation","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — conditional depletion with defined cellular phenotype, quantitative phosphoproteomics, and in vitro dephosphorylation assay identifying HP1-S33 as direct substrate, multiple orthogonal methods in single study","pmids":["40410154"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2014,"finding":"In P. berghei, knockout of PbPPM2 reduces female gametocyte production and alters the male-to-female ratio from approximately 1:3 (wild type) to 1:1 in the mutant, demonstrating a positive role for PPM2 in determining female-biased sex allocation. Ookinete conversion is also drastically impaired, blocked at early retort stage II, and ookinete ultrastructure analysis revealed a partial defect in microneme formation.","method":"Genetic knockout (gene deletion), gametocyte counting, ookinete conversion assay, electron microscopy of ookinete ultrastructure","journal":"Microorganisms (review citing Guttery et al. 2014); Cellular microbiology (review citing Guttery et al. 2014)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean KO with defined cellular phenotypes (sex ratio, ookinete morphology) replicated across multiple review citations of the same study; primary data not directly in this corpus","pmids":["35336160","27111866","25557077","34324911"],"is_preprint":false,"attribution":[{"species":"Plasmodium berghei","strain":""}]},{"year":2023,"finding":"In a phosphoproteomic study of PfPK2-depleted P. falciparum schizonts, PPM2 (PF3D7_1138500) was found to be hyperphosphorylated upon PfPK2 depletion, suggesting that PfPK2 acts upstream of PPM2 phosphorylation status (directly or indirectly). The authors proposed this may contribute to the aberrant phosphorylation of downstream proteins, but the directionality was not experimentally confirmed.","method":"Quantitative phosphoproteomics on conditional PfPK2-loxP knockdown parasites","journal":"PLoS pathogens","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single phosphoproteomic observation, no direct mechanistic follow-up on PPM2 itself, authors note it as correlative","pmids":["37988347"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2024,"finding":"A meta-analysis of 11 phosphoproteomic datasets identified multiple phosphorylation sites on PPM2 (PF3D7_1138500) in P. falciparum. Structurally conserved (core) residues carry fully conserved phosphosites across the Plasmodium genus, while intrinsically disordered regions outside the core carry non-conserved phosphosites unique to P. falciparum.","method":"Phosphoproteomics meta-analysis, AlphaFold structural mapping, cross-species conservation analysis","journal":"Journal of proteome research","confidence":"Low","confidence_rationale":"Tier 4 / Weak — computational/meta-analytic mapping of phosphosites, no functional experiment performed on PPM2 itself","pmids":["39475123"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]}],"current_model":"PPM2 (PF3D7_1138500) is an unusually large, dimeric Mg2+/Mn2+-dependent PP2C-family phosphatase whose two catalytic halves interact and whose dimerization is required for optimal activity; in P. falciparum it regulates asexual division and sexual commitment by directly dephosphorylating Heterochromatin Protein 1 at S33 (promoting HP1–H3K9me3–chromatin interactions required for sexual conversion) and by repressing eIF2α phosphorylation to support protein synthesis, while in P. berghei its loss reduces female gametocyte production (shifting the sex ratio toward parity) and blocks ookinete development at the retort stage with microneme defects."},"narrative":{"mechanistic_narrative":"PPM2 (PF3D7_1138500) is an unusually large PP2C-family serine/threonine phosphatase in Plasmodium that governs the transition between asexual replication and sexual commitment [PMID:9556615, PMID:40410154]. It comprises two complete catalytic halves, each with independent Mg2+/Mn2+-dependent phosphatase activity toward casein, and the full-length protein forms a dimer whose assembly is required for optimal activity; either half alone is sufficient to complement the S. pombe ptc1Δ heat-shock defect [PMID:9556615]. In P. falciparum, conditional depletion impairs asexual replication and reduces sexual conversion, and phosphoproteomics identifies Heterochromatin Protein 1 and translation initiation factor eIF2α as key substrates: PPM2 directly dephosphorylates HP1 at serine 33, promoting HP1–H3K9me3–chromatin association required for sexual commitment, and represses eIF2α phosphorylation to support protein synthesis during division [PMID:40410154]. In P. berghei, knockout reduces female gametocyte production, shifts the male-to-female ratio from ~1:3 toward 1:1, and blocks ookinete development at retort stage II with defective microneme formation [PMID:35336160, PMID:27111866, PMID:25557077, PMID:34324911].","teleology":[{"year":1998,"claim":"Established that PPM2 is a functional PP2C phosphatase with a novel bipartite architecture, resolving whether its two catalytic halves are independently active and whether the protein acts as a dimer.","evidence":"recombinant 32P-casein dephosphorylation assays, yeast two-hybrid, gel filtration, and S. pombe ptc1Δ complementation with domain dissection in P. falciparum","pmids":["9556615"],"confidence":"High","gaps":["No physiological substrate identified at this stage","Dimerization requirement shown biochemically but not in the parasite","No cellular phenotype linked to the enzymatic activity"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2014,"claim":"Placed PPM2 in the sexual/mosquito-stage program by showing it is required for female-biased sex allocation and ookinete maturation, the first in vivo functional role.","evidence":"gene knockout with gametocyte counting, ookinete conversion assay, and electron microscopy of ookinete ultrastructure in P. berghei","pmids":["35336160","27111866","25557077","34324911"],"confidence":"Medium","gaps":["Molecular substrates driving the sex-ratio and ookinete phenotypes not defined","Primary data represented only via review citations in this corpus","Connection to the P. falciparum asexual/commitment role not established"],"attribution":[{"species":"Plasmodium berghei","strain":""}]},{"year":2023,"claim":"Raised the possibility that PPM2 phosphorylation status is controlled upstream by a kinase, situating it in a broader signalling network.","evidence":"quantitative phosphoproteomics on conditional PfPK2-loxP knockdown P. falciparum schizonts showing PPM2 hyperphosphorylation","pmids":["37988347"],"confidence":"Low","gaps":["Correlative single observation; directionality and directness not experimentally confirmed","Effect of PPM2 phosphorylation on its activity unknown"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2024,"claim":"Mapped the phosphosite landscape of PPM2, distinguishing conserved core sites from lineage-specific sites in disordered regions.","evidence":"meta-analysis of 11 phosphoproteomic datasets with AlphaFold structural mapping and cross-species conservation analysis in P. falciparum","pmids":["39475123"],"confidence":"Low","gaps":["Computational only; no functional test of any phosphosite on PPM2","Regulatory consequence of core vs disordered-region phosphorylation unresolved"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2025,"claim":"Defined the direct molecular mechanism by which PPM2 controls the asexual-to-sexual switch, identifying HP1-S33 and eIF2α as substrates.","evidence":"auxin-inducible degron depletion, quantitative phosphoproteomics, in vitro HP1-S33 dephosphorylation, ChIP and co-immunoprecipitation in P. falciparum","pmids":["40410154"],"confidence":"High","gaps":["Mechanism coupling HP1 dephosphorylation timing to commitment decision not fully resolved","Whether eIF2α is a direct substrate not separately demonstrated in vitro","Relationship to the P. berghei mosquito-stage phenotypes not directly tested"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":null,"claim":"How PPM2's dimeric bipartite catalytic architecture, its own phosphoregulation, and its stage-specific substrate selection are integrated to switch parasites between replication, commitment, and transmission remains open.","evidence":"no single study connects the biochemical dimerization requirement, upstream phosphoregulation, and the divergent asexual/sexual/mosquito-stage phenotypes","pmids":[],"confidence":"Low","gaps":["No structure of the full-length dimer or substrate-bound complex","Upstream regulator controlling PPM2 activity not defined","Whether P. falciparum HP1/eIF2α mechanism explains the P. berghei transmission phenotypes untested"],"attribution":[]}],"mechanism_profile":{"molecular_activity":[],"localization":[],"pathway":[],"complexes":[],"partners":["HETEROCHROMATIN PROTEIN 1 (HP1) — DIRECT SUBSTRATE, DEPHOSPHORYLATED AT S33 [#1]","EIF2Α — TARGET REPRESSED BY PPM2 TO SUPPORT TRANSLATION [#1]","PFPK2 — KINASE UPSTREAM OF PPM2 PHOSPHORYLATION STATUS (CORRELATIVE) [#3]"],"other_free_text":["Bipartite phosphatase with two complete PP2C catalytic halves (Pf2C-1, Pf2C-2), each independently active and each able to complement S. pombe ptc1Δ [#0]","Functions as a dimer; dimerization required for optimal phosphatase activity [#0]","Multiple phosphosites mapped: conserved sites in structured core, lineage-specific sites in disordered regions [#4]","In P. berghei, loss shifts sex ratio toward parity and blocks ookinete development at retort stage II with microneme defects [#2]"]}},"prefetch_data":{},"corpus_meta":[{"pmid":"9556615","id":"PMC_9556615","title":"Identification and characterization of an unusual double serine/threonine protein phosphatase 2C in the malaria parasite Plasmodium falciparum.","date":"1998","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/9556615","citation_count":41,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["curated_ref"],"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":["PfPPM2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"39475123","id":"","title":"Phosphorylation in the Plasmodium falciparum Proteome: A Meta-Analysis of Publicly Available Data Sets.","date":"2024","source":"Journal of proteome research","url":"https://pubmed.ncbi.nlm.nih.gov/39475123","citation_count":0,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["PPM2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"39153438","id":"","title":"The phosphatase inhibitor BVT-948 can be used to efficiently screen functional sexual development proteins in the malaria parasite Plasmodium berghei.","date":"2024","source":"International journal for parasitology. Drugs and drug resistance","url":"https://pubmed.ncbi.nlm.nih.gov/39153438","citation_count":0,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["PPM2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"38892332","id":"","title":"Post-Translational Modifications of Proteins of Malaria Parasites during the Life Cycle.","date":"2024","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/38892332","citation_count":0,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["PPM2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"42363832","id":"","title":"Inhibition of PfCLK3 interferes with malaria parasite RNA splicing and explains the mechanism of action of a new class of antimalarial candidates.","date":"2026","source":"Antimicrobial agents and chemotherapy","url":"https://pubmed.ncbi.nlm.nih.gov/42363832","citation_count":0,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["PPM2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"35336160","id":"","title":"Deciphering the Role of Protein Phosphatases in Apicomplexa: The Future of Innovative Therapeutics?","date":"2022","source":"Microorganisms","url":"https://pubmed.ncbi.nlm.nih.gov/35336160","citation_count":0,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["PPM2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"37988347","id":"","title":"Protein kinase PfPK2 mediated signalling is critical for host erythrocyte invasion by malaria parasite.","date":"2023","source":"PLoS pathogens","url":"https://pubmed.ncbi.nlm.nih.gov/37988347","citation_count":0,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["PPM2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"34324911","id":"","title":"Beyond phosphorylation: Putative roles of post-translational modifications in Plasmodium sexual stages.","date":"2021","source":"Molecular and biochemical parasitology","url":"https://pubmed.ncbi.nlm.nih.gov/34324911","citation_count":0,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["PPM2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"27111866","id":"","title":"The development of malaria parasites in the mosquito midgut.","date":"2016","source":"Cellular microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/27111866","citation_count":0,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["PPM2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"25557077","id":"","title":"The cell biology of malaria infection of mosquito: advances and opportunities.","date":"2015","source":"Cellular microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/25557077","citation_count":0,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["PPM2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":11824,"output_tokens":1903,"usd":0.032009,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":7038,"output_tokens":2783,"usd":0.052382,"stage2_stop_reason":"end_turn"},"total_usd":0.084391,"stage1_batch_id":"msgbatch_01SRp5hyRc82zNjddxyCCXGk","stage2_batch_id":"msgbatch_01K3BTmBazRo3pRrMvyaPMTY","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1998,\n      \"finding\": \"PPM2 (PF3D7_1138500) encodes an unusually large (~920 aa) PP2C-family phosphatase in P. falciparum that contains two complete catalytic halves (Pf2C-1 and Pf2C-2), each possessing independent Mg2+/Mn2+-dependent serine/threonine phosphatase activity as demonstrated by dephosphorylation of 32P-labeled casein in vitro. Yeast two-hybrid and gel filtration of parasite extracts demonstrated that the two halves interact and that the full-length protein forms a dimer, and phosphatase competition experiments showed that dimerization is required for optimal activity. Each half alone can complement the heat-shock response defect of a S. pombe ptc1Δ mutant, as can the full-length protein or a chimeric construct.\",\n      \"method\": \"Recombinant protein phosphatase assay (32P-casein dephosphorylation), yeast two-hybrid, gel filtration, S. pombe complementation, site-directed domain dissection\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro enzymatic reconstitution with mutagenesis-level domain dissection, orthogonal yeast genetics (complementation + two-hybrid), and gel filtration all in one study\",\n      \"pmids\": [\"9556615\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"PPM2 (PF3D7_1138500) regulates both asexual division and sexual commitment in P. falciparum. Conditional depletion of PfPPM2 impairs asexual replication and reduces sexual conversion. Comparative phosphoproteomics after PfPPM2 depletion identified Heterochromatin Protein 1 (HP1) and translation initiation factor eIF2α as key targets: PfPPM2 directly dephosphorylates HP1 at serine 33, and this dephosphorylation promotes the interaction of HP1 with H3K9me3 and chromatin that is required for sexual commitment. PfPPM2 also represses eIF2α phosphorylation, thereby supporting protein synthesis during parasite division.\",\n      \"method\": \"Conditional knockdown (AID/auxin-inducible degron), quantitative phosphoproteomics, in vitro phosphatase assay (dephosphorylation of HP1-S33), chromatin immunoprecipitation, co-immunoprecipitation\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — conditional depletion with defined cellular phenotype, quantitative phosphoproteomics, and in vitro dephosphorylation assay identifying HP1-S33 as direct substrate, multiple orthogonal methods in single study\",\n      \"pmids\": [\"40410154\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"In P. berghei, knockout of PbPPM2 reduces female gametocyte production and alters the male-to-female ratio from approximately 1:3 (wild type) to 1:1 in the mutant, demonstrating a positive role for PPM2 in determining female-biased sex allocation. Ookinete conversion is also drastically impaired, blocked at early retort stage II, and ookinete ultrastructure analysis revealed a partial defect in microneme formation.\",\n      \"method\": \"Genetic knockout (gene deletion), gametocyte counting, ookinete conversion assay, electron microscopy of ookinete ultrastructure\",\n      \"journal\": \"Microorganisms (review citing Guttery et al. 2014); Cellular microbiology (review citing Guttery et al. 2014)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean KO with defined cellular phenotypes (sex ratio, ookinete morphology) replicated across multiple review citations of the same study; primary data not directly in this corpus\",\n      \"pmids\": [\"35336160\", \"27111866\", \"25557077\", \"34324911\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium berghei\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"In a phosphoproteomic study of PfPK2-depleted P. falciparum schizonts, PPM2 (PF3D7_1138500) was found to be hyperphosphorylated upon PfPK2 depletion, suggesting that PfPK2 acts upstream of PPM2 phosphorylation status (directly or indirectly). The authors proposed this may contribute to the aberrant phosphorylation of downstream proteins, but the directionality was not experimentally confirmed.\",\n      \"method\": \"Quantitative phosphoproteomics on conditional PfPK2-loxP knockdown parasites\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single phosphoproteomic observation, no direct mechanistic follow-up on PPM2 itself, authors note it as correlative\",\n      \"pmids\": [\"37988347\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"A meta-analysis of 11 phosphoproteomic datasets identified multiple phosphorylation sites on PPM2 (PF3D7_1138500) in P. falciparum. Structurally conserved (core) residues carry fully conserved phosphosites across the Plasmodium genus, while intrinsically disordered regions outside the core carry non-conserved phosphosites unique to P. falciparum.\",\n      \"method\": \"Phosphoproteomics meta-analysis, AlphaFold structural mapping, cross-species conservation analysis\",\n      \"journal\": \"Journal of proteome research\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 4 / Weak — computational/meta-analytic mapping of phosphosites, no functional experiment performed on PPM2 itself\",\n      \"pmids\": [\"39475123\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    }\n  ],\n  \"current_model\": \"PPM2 (PF3D7_1138500) is an unusually large, dimeric Mg2+/Mn2+-dependent PP2C-family phosphatase whose two catalytic halves interact and whose dimerization is required for optimal activity; in P. falciparum it regulates asexual division and sexual commitment by directly dephosphorylating Heterochromatin Protein 1 at S33 (promoting HP1–H3K9me3–chromatin interactions required for sexual conversion) and by repressing eIF2α phosphorylation to support protein synthesis, while in P. berghei its loss reduces female gametocyte production (shifting the sex ratio toward parity) and blocks ookinete development at the retort stage with microneme defects.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"PPM2 (PF3D7_1138500) is an unusually large PP2C-family serine/threonine phosphatase in Plasmodium that governs the transition between asexual replication and sexual commitment [#0, #1]. It comprises two complete catalytic halves, each with independent Mg2+/Mn2+-dependent phosphatase activity toward casein, and the full-length protein forms a dimer whose assembly is required for optimal activity; either half alone is sufficient to complement the S. pombe ptc1Δ heat-shock defect [#0]. In P. falciparum, conditional depletion impairs asexual replication and reduces sexual conversion, and phosphoproteomics identifies Heterochromatin Protein 1 and translation initiation factor eIF2α as key substrates: PPM2 directly dephosphorylates HP1 at serine 33, promoting HP1–H3K9me3–chromatin association required for sexual commitment, and represses eIF2α phosphorylation to support protein synthesis during division [#1]. In P. berghei, knockout reduces female gametocyte production, shifts the male-to-female ratio from ~1:3 toward 1:1, and blocks ookinete development at retort stage II with defective microneme formation [#2].\",\n  \"teleology\": [\n    {\n      \"year\": 1998,\n      \"claim\": \"Established that PPM2 is a functional PP2C phosphatase with a novel bipartite architecture, resolving whether its two catalytic halves are independently active and whether the protein acts as a dimer.\",\n      \"evidence\": \"recombinant 32P-casein dephosphorylation assays, yeast two-hybrid, gel filtration, and S. pombe ptc1Δ complementation with domain dissection in P. falciparum\",\n      \"pmids\": [\"9556615\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"No physiological substrate identified at this stage\",\n        \"Dimerization requirement shown biochemically but not in the parasite\",\n        \"No cellular phenotype linked to the enzymatic activity\"\n      ],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Placed PPM2 in the sexual/mosquito-stage program by showing it is required for female-biased sex allocation and ookinete maturation, the first in vivo functional role.\",\n      \"evidence\": \"gene knockout with gametocyte counting, ookinete conversion assay, and electron microscopy of ookinete ultrastructure in P. berghei\",\n      \"pmids\": [\"35336160\", \"27111866\", \"25557077\", \"34324911\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Molecular substrates driving the sex-ratio and ookinete phenotypes not defined\",\n        \"Primary data represented only via review citations in this corpus\",\n        \"Connection to the P. falciparum asexual/commitment role not established\"\n      ],\n      \"attribution\": [{\"species\": \"Plasmodium berghei\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Raised the possibility that PPM2 phosphorylation status is controlled upstream by a kinase, situating it in a broader signalling network.\",\n      \"evidence\": \"quantitative phosphoproteomics on conditional PfPK2-loxP knockdown P. falciparum schizonts showing PPM2 hyperphosphorylation\",\n      \"pmids\": [\"37988347\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"Correlative single observation; directionality and directness not experimentally confirmed\",\n        \"Effect of PPM2 phosphorylation on its activity unknown\"\n      ],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Mapped the phosphosite landscape of PPM2, distinguishing conserved core sites from lineage-specific sites in disordered regions.\",\n      \"evidence\": \"meta-analysis of 11 phosphoproteomic datasets with AlphaFold structural mapping and cross-species conservation analysis in P. falciparum\",\n      \"pmids\": [\"39475123\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"Computational only; no functional test of any phosphosite on PPM2\",\n        \"Regulatory consequence of core vs disordered-region phosphorylation unresolved\"\n      ],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Defined the direct molecular mechanism by which PPM2 controls the asexual-to-sexual switch, identifying HP1-S33 and eIF2α as substrates.\",\n      \"evidence\": \"auxin-inducible degron depletion, quantitative phosphoproteomics, in vitro HP1-S33 dephosphorylation, ChIP and co-immunoprecipitation in P. falciparum\",\n      \"pmids\": [\"40410154\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Mechanism coupling HP1 dephosphorylation timing to commitment decision not fully resolved\",\n        \"Whether eIF2α is a direct substrate not separately demonstrated in vitro\",\n        \"Relationship to the P. berghei mosquito-stage phenotypes not directly tested\"\n      ],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How PPM2's dimeric bipartite catalytic architecture, its own phosphoregulation, and its stage-specific substrate selection are integrated to switch parasites between replication, commitment, and transmission remains open.\",\n      \"evidence\": \"no single study connects the biochemical dimerization requirement, upstream phosphoregulation, and the divergent asexual/sexual/mosquito-stage phenotypes\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"No structure of the full-length dimer or substrate-bound complex\",\n        \"Upstream regulator controlling PPM2 activity not defined\",\n        \"Whether P. falciparum HP1/eIF2α mechanism explains the P. berghei transmission phenotypes untested\"\n      ],\n      \"attribution\": []\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0004722\", \"supporting_discovery_ids\": [0, 1]},\n      {\"term_id\": \"GO:0046872\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"GO:0042803\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0000785\", \"supporting_discovery_ids\": [1]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0060179\", \"supporting_discovery_ids\": [1, 2]},\n      {\"term_id\": \"GO:0006417\", \"supporting_discovery_ids\": [1]},\n      {\"term_id\": \"GO:0031507\", \"supporting_discovery_ids\": [1]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"Heterochromatin Protein 1 (HP1) — direct substrate, dephosphorylated at S33 [#1]\",\n      \"eIF2α — target repressed by PPM2 to support translation [#1]\",\n      \"PfPK2 — kinase upstream of PPM2 phosphorylation status (correlative) [#3]\"\n    ],\n    \"other_free_text\": [\n      \"Bipartite phosphatase with two complete PP2C catalytic halves (Pf2C-1, Pf2C-2), each independently active and each able to complement S. pombe ptc1Δ [#0]\",\n      \"Functions as a dimer; dimerization required for optimal phosphatase activity [#0]\",\n      \"Multiple phosphosites mapped: conserved sites in structured core, lineage-specific sites in disordered regions [#4]\",\n      \"In P. berghei, loss shifts sex ratio toward parity and blocks ookinete development at retort stage II with microneme defects [#2]\"\n    ]\n  }\n}","audit_flag":null,"strains":[{"strain":"Pf3D7","gene_id":"PF3D7_1138500","name":null,"product":"protein phosphatase PPM2, protein phosphatase 2C","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PbANKA","gene_id":"PBANKA_0910200","name":null,"product":"protein phosphatase PPM2","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PkH","gene_id":"PKNH_0936700","name":null,"product":"protein phosphatase PPM2, putative","uniprot_acc":null,"chromosome":null,"start_pos":null}],"gene_symbol":"PPM2","evaluation":null}