{"gene":"PF3D7_1031600","run_date":"2026-09-08T12:51:28","timeline":{"discoveries":[{"year":2010,"finding":"GEXP15 (PF3D7_1031600) is enriched in the early gametocyte proteome of P. falciparum and is among the exported proteins detected in the erythrocyte cytoplasm during early gametocytogenesis; mass spectrometry detected N-terminal processing and N-acetylation at a conserved leucine residue within the PEXEL/HT pentamotif in early but not mature gametocyte samples, supporting a role in protein export during early sexual differentiation.","method":"Quantitative label-free comparative proteomics (high-accuracy tandem mass spectrometry) of purified early gametocytes; N-terminal peptide detection by MS","journal":"Molecular & cellular proteomics : MCP","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — mass spectrometry with proteomic quantification across stages in a single lab; N-terminal processing detected by MS but functional consequence not fully dissected","pmids":["20332084"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2019,"finding":"GEXP15 (PF3D7_1031600) physically interacts with Protein Phosphatase type 1 (PP1) through an RVxF binding motif in P. berghei; this interaction was demonstrated by in vitro interaction studies and confirmed by immunoprecipitation of tagged GEXP15 or PP1 followed by immunoblot and mass spectrometry.","method":"In vitro pull-down interaction assay; co-immunoprecipitation of tagged protein followed by immunoblot and mass spectrometry","journal":"PLoS pathogens","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP confirmed by MS, supported by in vitro interaction assay with RVxF motif mutagenesis, replicated in two species","pmids":["31348803"],"is_preprint":false,"attribution":[{"species":"Plasmodium berghei","strain":""}]},{"year":2019,"finding":"GEXP15 increases PP1 phosphatase activity in P. berghei, and mutation of the RVxF motif completely abolishes this regulatory effect.","method":"Functional in vitro phosphatase activity assay with wild-type and RVxF-mutant GEXP15","journal":"PLoS pathogens","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro enzymatic activity assay with active-site/motif mutagenesis, single lab","pmids":["31348803"],"is_preprint":false,"attribution":[{"species":"Plasmodium berghei","strain":""}]},{"year":2019,"finding":"GEXP15 and PP1 are present in shared protein complexes in both schizont and gametocyte stages in P. berghei, and these complexes include components of the spliceosome and proteasome pathways.","method":"Immunoprecipitation of tagged GEXP15 or PP1 followed by mass spectrometry","journal":"PLoS pathogens","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP followed by MS in two independent tagged lines (GEXP15 and PP1), single lab","pmids":["31348803"],"is_preprint":false,"attribution":[{"species":"Plasmodium berghei","strain":""}]},{"year":2019,"finding":"GEXP15-deficient P. berghei blood-stage parasites are unable to develop lethal infection in BALB/c mice, fail to establish cerebral malaria in C57BL/6 mice, and produce gametocytes but no oocysts or sporozoites, demonstrating an essential role in both asexual proliferation and mosquito transmission.","method":"Genetic knockout of GEXP15 in P. berghei; in vivo infection assays in BALB/c and C57BL/6 mice; mosquito feeding assays","journal":"PLoS pathogens","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean genetic KO with multiple defined in vivo phenotypic readouts across asexual and sexual stages","pmids":["31348803"],"is_preprint":false,"attribution":[{"species":"Plasmodium berghei","strain":""}]},{"year":2019,"finding":"Global proteomic and phosphoproteomic analysis of GEXP15-deficient P. berghei schizonts revealed significant decreases in abundance and altered phosphorylation status of proteins involved in regulation of gene expression and invasion, and depletion of GEXP15 impacted abundance of specific female gametocyte proteins.","method":"Global proteomics and phosphoproteomics by mass spectrometry of GEXP15 knockout vs. wild-type schizonts","journal":"PLoS pathogens","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — quantitative phosphoproteomics on KO parasites, single lab, single study","pmids":["31348803"],"is_preprint":false,"attribution":[{"species":"Plasmodium berghei","strain":""}]},{"year":2023,"finding":"GEXP15 (PF3D7_1031600) directly interacts with PP1 (PF3D7_1414400) via an RVxF-binding motif in P. falciparum, and this interaction enhances PP1 phosphatase activity, as confirmed by in vitro interaction and functional assays.","method":"In vitro pull-down interaction assay; in vitro phosphatase activity assay with recombinant proteins","journal":"International journal of molecular sciences","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution of interaction and enzymatic activity assay, single lab, corroborates P. berghei findings","pmids":["37628837"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2023,"finding":"In silico analysis identified three structural/functional regions in PfGEXP15: an N-terminal region containing a PP1-interacting RVxF motif, a conserved domain of unknown function, and a GYF-like domain predicted to mediate protein-protein interactions.","method":"In silico structural analysis","journal":"International journal of molecular sciences","confidence":"Low","confidence_rationale":"Tier 4 / Weak — computational prediction only, no experimental validation of domain boundaries beyond GYF pull-down","pmids":["37628837"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2023,"finding":"PfGEXP15 is highly expressed in late asexual (schizont) stages and localizes predominantly to the nucleus, as determined by live microscopy of a transgenic GEXP15-tagged P. falciparum line.","method":"Live fluorescence microscopy of transgenic tagged parasite line","journal":"International journal of molecular sciences","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — direct localization by live imaging in tagged line, single lab, single method","pmids":["37628837"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2023,"finding":"Immunoprecipitation of PfGEXP15 followed by mass spectrometry revealed interaction with ribosomal and RNA-binding proteins; pull-down assays with recombinant His-tagged GYF domain confirmed binding to the ribosomal complex via the GYF domain of GEXP15.","method":"Co-immunoprecipitation followed by mass spectrometry; pull-down assay with recombinant His-tagged GYF domain","journal":"International journal of molecular sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP/MS and orthogonal domain-specific pull-down, single lab","pmids":["37628837"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]}],"current_model":"PfGEXP15 (PF3D7_1031600) is a Plasmodium-specific nuclear protein expressed in late asexual and gametocyte stages that directly binds PP1 phosphatase via an RVxF motif to enhance its activity, associates with ribosomal/RNA-binding proteins via its GYF-like domain, is exported to the erythrocyte cytoplasm during early gametocytogenesis with N-terminal PEXEL processing, and is essential for asexual blood-stage proliferation and mosquito transmission in P. berghei."},"narrative":{"mechanistic_narrative":"GEXP15 (PF3D7_1031600) is a Plasmodium nuclear protein that functions as a regulator of Protein Phosphatase type 1 (PP1) and is essential for parasite proliferation and transmission [PMID:31348803]. It binds PP1 directly through an N-terminal RVxF docking motif and enhances the phosphatase's catalytic activity, an effect abolished by mutation of the RVxF motif; this PP1-regulatory interaction is conserved between P. berghei and P. falciparum [PMID:31348803, PMID:37628837]. Beyond PP1, GEXP15 associates with larger complexes: in P. berghei it is recovered alongside PP1 in schizont- and gametocyte-stage complexes that include spliceosome and proteasome components [PMID:31348803], and in P. falciparum its GYF-like domain mediates binding to ribosomal and RNA-binding proteins [PMID:37628837]. In P. falciparum GEXP15 is most highly expressed in schizonts and localizes predominantly to the nucleus [PMID:37628837], while in the early gametocyte proteome it is detected as an exported protein in the erythrocyte cytoplasm with N-terminal PEXEL/HT processing and N-acetylation [PMID:20332084]. Genetic ablation in P. berghei prevents lethal and cerebral malaria infection and blocks oocyst and sporozoite formation despite gametocyte production, and phosphoproteomic profiling of knockout schizonts shows altered abundance and phosphorylation of proteins involved in gene expression regulation and invasion [PMID:31348803], consistent with GEXP15 acting as a PP1 regulatory partner controlling parasite phosphosignaling.","teleology":[{"year":2010,"claim":"Establishing GEXP15 as a stage-regulated, exported protein first placed it in the biology of early sexual differentiation, before any molecular activity was known.","evidence":"Quantitative label-free comparative proteomics and N-terminal peptide detection in purified P. falciparum early gametocytes","pmids":["20332084"],"confidence":"Medium","gaps":["Functional consequence of PEXEL/HT N-terminal processing and N-acetylation not tested","Export mechanism and destination within the erythrocyte not resolved","No link yet to a molecular activity"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2019,"claim":"Identifying GEXP15 as an RVxF-motif PP1 partner that boosts phosphatase activity defined its core molecular function as a PP1 regulatory protein.","evidence":"In vitro pull-down, reciprocal Co-IP/MS, and in vitro phosphatase activity assays with wild-type and RVxF-mutant GEXP15 in P. berghei","pmids":["31348803"],"confidence":"High","gaps":["Substrates whose dephosphorylation is controlled by the GEXP15–PP1 complex not directly identified","Structural basis of activity enhancement not resolved","Whether GEXP15 targets PP1 to specific substrates or subcellular sites unknown"],"attribution":[{"species":"Plasmodium berghei","strain":""}]},{"year":2019,"claim":"Demonstrating that GEXP15 co-purifies with PP1 in spliceosome- and proteasome-containing complexes placed the phosphatase regulator within larger machinery across asexual and sexual stages.","evidence":"Immunoprecipitation of tagged GEXP15 or PP1 followed by mass spectrometry in P. berghei schizonts and gametocytes","pmids":["31348803"],"confidence":"Medium","gaps":["Direct versus indirect nature of spliceosome/proteasome associations not distinguished","Functional role of GEXP15 within these complexes not tested","Stage-specific composition of the complexes not fully resolved"],"attribution":[{"species":"Plasmodium berghei","strain":""}]},{"year":2019,"claim":"Genetic knockout established that GEXP15 is essential for both asexual blood-stage proliferation and mosquito-stage transmission, moving it from an associated factor to a required regulator.","evidence":"GEXP15 knockout in P. berghei with in vivo infection assays in BALB/c and C57BL/6 mice and mosquito feeding assays; global proteomics/phosphoproteomics of KO schizonts","pmids":["31348803"],"confidence":"High","gaps":["Causal chain from GEXP15 loss to the transmission block not defined","Which altered phosphorylation events drive the phenotype not established","Essentiality not tested in P. falciparum"],"attribution":[{"species":"Plasmodium berghei","strain":""}]},{"year":2023,"claim":"Confirming the RVxF-dependent PP1 interaction in P. falciparum and mapping a GYF-domain link to ribosomal/RNA-binding proteins extended the PP1-regulator model to the human pathogen and identified a second interaction interface.","evidence":"In vitro pull-down and phosphatase assays with recombinant proteins, Co-IP/MS, GYF-domain pull-down, live imaging, and in silico domain analysis in P. falciparum","pmids":["37628837"],"confidence":"High","gaps":["Functional consequence of GEXP15 binding ribosomal/RNA-binding proteins not tested","Domain boundaries and the conserved domain of unknown function not experimentally validated","How nuclear localization reconciles with the earlier exported/erythrocyte detection not addressed"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":null,"claim":"The physiological substrates and biological processes controlled by the GEXP15–PP1 complex, and how its ribosomal/RNA-binding and nuclear activities integrate with phosphatase regulation, remain unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No direct PP1 substrate assigned to GEXP15 regulation","Mechanistic role of the GYF-domain ribosomal interaction unknown","No structural model of the GEXP15–PP1 complex"],"attribution":[{"species":"Plasmodium berghei","strain":""},{"species":"Plasmodium falciparum","strain":""}]}],"mechanism_profile":{"molecular_activity":[],"localization":[],"pathway":[],"complexes":["GEXP15–PP1 complex","PP1-associated spliceosome-containing complex (P. berghei)","PP1-associated proteasome-containing complex (P. berghei)","GYF-domain ribosomal complex (P. falciparum)"],"partners":["PP1 (PF3D7_1414400)","RIBOSOMAL PROTEINS","RNA-BINDING PROTEINS"],"other_free_text":["N-terminal RVxF PP1-docking motif required for PP1 binding and activity enhancement [#2, #6]","GYF-like domain mediates binding to ribosomal complex [#7, #9]","Conserved domain of unknown function predicted but not experimentally characterized [#7]","N-terminal PEXEL/HT processing and N-acetylation detected in early gametocytes [#0]","Essential for asexual proliferation and mosquito transmission in P. berghei [#4]"]}},"prefetch_data":{},"corpus_meta":[{"pmid":"20332084","id":"PMC_20332084","title":"Protein export marks the early phase of gametocytogenesis of the human malaria parasite Plasmodium falciparum.","date":"2010","source":"Molecular & cellular proteomics : MCP","url":"https://pubmed.ncbi.nlm.nih.gov/20332084","citation_count":216,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["curated_ref"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"31348803","id":"PMC_31348803","title":"Essential role of GEXP15, a specific Protein Phosphatase type 1 partner, in Plasmodium berghei in asexual erythrocytic proliferation and transmission.","date":"2019","source":"PLoS pathogens","url":"https://pubmed.ncbi.nlm.nih.gov/31348803","citation_count":15,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["GEXP15"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"37628837","id":"PMC_37628837","title":"Characterization of GEXP15 as a Potential Regulator of Protein Phosphatase 1 in Plasmodium falciparum.","date":"2023","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/37628837","citation_count":1,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["GEXP15","PfGEXP15"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":4691,"output_tokens":2512,"usd":0.025877,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":7936,"output_tokens":2984,"usd":0.05714,"stage2_stop_reason":"end_turn"},"total_usd":0.083017,"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\": 2010,\n      \"finding\": \"GEXP15 (PF3D7_1031600) is enriched in the early gametocyte proteome of P. falciparum and is among the exported proteins detected in the erythrocyte cytoplasm during early gametocytogenesis; mass spectrometry detected N-terminal processing and N-acetylation at a conserved leucine residue within the PEXEL/HT pentamotif in early but not mature gametocyte samples, supporting a role in protein export during early sexual differentiation.\",\n      \"method\": \"Quantitative label-free comparative proteomics (high-accuracy tandem mass spectrometry) of purified early gametocytes; N-terminal peptide detection by MS\",\n      \"journal\": \"Molecular & cellular proteomics : MCP\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — mass spectrometry with proteomic quantification across stages in a single lab; N-terminal processing detected by MS but functional consequence not fully dissected\",\n      \"pmids\": [\"20332084\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"GEXP15 (PF3D7_1031600) physically interacts with Protein Phosphatase type 1 (PP1) through an RVxF binding motif in P. berghei; this interaction was demonstrated by in vitro interaction studies and confirmed by immunoprecipitation of tagged GEXP15 or PP1 followed by immunoblot and mass spectrometry.\",\n      \"method\": \"In vitro pull-down interaction assay; co-immunoprecipitation of tagged protein followed by immunoblot and mass spectrometry\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP confirmed by MS, supported by in vitro interaction assay with RVxF motif mutagenesis, replicated in two species\",\n      \"pmids\": [\"31348803\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium berghei\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"GEXP15 increases PP1 phosphatase activity in P. berghei, and mutation of the RVxF motif completely abolishes this regulatory effect.\",\n      \"method\": \"Functional in vitro phosphatase activity assay with wild-type and RVxF-mutant GEXP15\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro enzymatic activity assay with active-site/motif mutagenesis, single lab\",\n      \"pmids\": [\"31348803\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium berghei\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"GEXP15 and PP1 are present in shared protein complexes in both schizont and gametocyte stages in P. berghei, and these complexes include components of the spliceosome and proteasome pathways.\",\n      \"method\": \"Immunoprecipitation of tagged GEXP15 or PP1 followed by mass spectrometry\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP followed by MS in two independent tagged lines (GEXP15 and PP1), single lab\",\n      \"pmids\": [\"31348803\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium berghei\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"GEXP15-deficient P. berghei blood-stage parasites are unable to develop lethal infection in BALB/c mice, fail to establish cerebral malaria in C57BL/6 mice, and produce gametocytes but no oocysts or sporozoites, demonstrating an essential role in both asexual proliferation and mosquito transmission.\",\n      \"method\": \"Genetic knockout of GEXP15 in P. berghei; in vivo infection assays in BALB/c and C57BL/6 mice; mosquito feeding assays\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean genetic KO with multiple defined in vivo phenotypic readouts across asexual and sexual stages\",\n      \"pmids\": [\"31348803\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium berghei\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Global proteomic and phosphoproteomic analysis of GEXP15-deficient P. berghei schizonts revealed significant decreases in abundance and altered phosphorylation status of proteins involved in regulation of gene expression and invasion, and depletion of GEXP15 impacted abundance of specific female gametocyte proteins.\",\n      \"method\": \"Global proteomics and phosphoproteomics by mass spectrometry of GEXP15 knockout vs. wild-type schizonts\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — quantitative phosphoproteomics on KO parasites, single lab, single study\",\n      \"pmids\": [\"31348803\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium berghei\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"GEXP15 (PF3D7_1031600) directly interacts with PP1 (PF3D7_1414400) via an RVxF-binding motif in P. falciparum, and this interaction enhances PP1 phosphatase activity, as confirmed by in vitro interaction and functional assays.\",\n      \"method\": \"In vitro pull-down interaction assay; in vitro phosphatase activity assay with recombinant proteins\",\n      \"journal\": \"International journal of molecular sciences\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution of interaction and enzymatic activity assay, single lab, corroborates P. berghei findings\",\n      \"pmids\": [\"37628837\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"In silico analysis identified three structural/functional regions in PfGEXP15: an N-terminal region containing a PP1-interacting RVxF motif, a conserved domain of unknown function, and a GYF-like domain predicted to mediate protein-protein interactions.\",\n      \"method\": \"In silico structural analysis\",\n      \"journal\": \"International journal of molecular sciences\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 4 / Weak — computational prediction only, no experimental validation of domain boundaries beyond GYF pull-down\",\n      \"pmids\": [\"37628837\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"PfGEXP15 is highly expressed in late asexual (schizont) stages and localizes predominantly to the nucleus, as determined by live microscopy of a transgenic GEXP15-tagged P. falciparum line.\",\n      \"method\": \"Live fluorescence microscopy of transgenic tagged parasite line\",\n      \"journal\": \"International journal of molecular sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — direct localization by live imaging in tagged line, single lab, single method\",\n      \"pmids\": [\"37628837\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Immunoprecipitation of PfGEXP15 followed by mass spectrometry revealed interaction with ribosomal and RNA-binding proteins; pull-down assays with recombinant His-tagged GYF domain confirmed binding to the ribosomal complex via the GYF domain of GEXP15.\",\n      \"method\": \"Co-immunoprecipitation followed by mass spectrometry; pull-down assay with recombinant His-tagged GYF domain\",\n      \"journal\": \"International journal of molecular sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP/MS and orthogonal domain-specific pull-down, single lab\",\n      \"pmids\": [\"37628837\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    }\n  ],\n  \"current_model\": \"PfGEXP15 (PF3D7_1031600) is a Plasmodium-specific nuclear protein expressed in late asexual and gametocyte stages that directly binds PP1 phosphatase via an RVxF motif to enhance its activity, associates with ribosomal/RNA-binding proteins via its GYF-like domain, is exported to the erythrocyte cytoplasm during early gametocytogenesis with N-terminal PEXEL processing, and is essential for asexual blood-stage proliferation and mosquito transmission in P. berghei.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"GEXP15 (PF3D7_1031600) is a Plasmodium nuclear protein that functions as a regulator of Protein Phosphatase type 1 (PP1) and is essential for parasite proliferation and transmission [#1, #4]. It binds PP1 directly through an N-terminal RVxF docking motif and enhances the phosphatase's catalytic activity, an effect abolished by mutation of the RVxF motif; this PP1-regulatory interaction is conserved between P. berghei and P. falciparum [#2, #6]. Beyond PP1, GEXP15 associates with larger complexes: in P. berghei it is recovered alongside PP1 in schizont- and gametocyte-stage complexes that include spliceosome and proteasome components [#3], and in P. falciparum its GYF-like domain mediates binding to ribosomal and RNA-binding proteins [#9]. In P. falciparum GEXP15 is most highly expressed in schizonts and localizes predominantly to the nucleus [#8], while in the early gametocyte proteome it is detected as an exported protein in the erythrocyte cytoplasm with N-terminal PEXEL/HT processing and N-acetylation [#0]. Genetic ablation in P. berghei prevents lethal and cerebral malaria infection and blocks oocyst and sporozoite formation despite gametocyte production, and phosphoproteomic profiling of knockout schizonts shows altered abundance and phosphorylation of proteins involved in gene expression regulation and invasion [#4, #5], consistent with GEXP15 acting as a PP1 regulatory partner controlling parasite phosphosignaling.\",\n  \"teleology\": [\n    {\n      \"year\": 2010,\n      \"claim\": \"Establishing GEXP15 as a stage-regulated, exported protein first placed it in the biology of early sexual differentiation, before any molecular activity was known.\",\n      \"evidence\": \"Quantitative label-free comparative proteomics and N-terminal peptide detection in purified P. falciparum early gametocytes\",\n      \"pmids\": [\"20332084\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional consequence of PEXEL/HT N-terminal processing and N-acetylation not tested\", \"Export mechanism and destination within the erythrocyte not resolved\", \"No link yet to a molecular activity\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Identifying GEXP15 as an RVxF-motif PP1 partner that boosts phosphatase activity defined its core molecular function as a PP1 regulatory protein.\",\n      \"evidence\": \"In vitro pull-down, reciprocal Co-IP/MS, and in vitro phosphatase activity assays with wild-type and RVxF-mutant GEXP15 in P. berghei\",\n      \"pmids\": [\"31348803\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Substrates whose dephosphorylation is controlled by the GEXP15–PP1 complex not directly identified\", \"Structural basis of activity enhancement not resolved\", \"Whether GEXP15 targets PP1 to specific substrates or subcellular sites unknown\"],\n      \"attribution\": [{\"species\": \"Plasmodium berghei\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Demonstrating that GEXP15 co-purifies with PP1 in spliceosome- and proteasome-containing complexes placed the phosphatase regulator within larger machinery across asexual and sexual stages.\",\n      \"evidence\": \"Immunoprecipitation of tagged GEXP15 or PP1 followed by mass spectrometry in P. berghei schizonts and gametocytes\",\n      \"pmids\": [\"31348803\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct versus indirect nature of spliceosome/proteasome associations not distinguished\", \"Functional role of GEXP15 within these complexes not tested\", \"Stage-specific composition of the complexes not fully resolved\"],\n      \"attribution\": [{\"species\": \"Plasmodium berghei\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Genetic knockout established that GEXP15 is essential for both asexual blood-stage proliferation and mosquito-stage transmission, moving it from an associated factor to a required regulator.\",\n      \"evidence\": \"GEXP15 knockout in P. berghei with in vivo infection assays in BALB/c and C57BL/6 mice and mosquito feeding assays; global proteomics/phosphoproteomics of KO schizonts\",\n      \"pmids\": [\"31348803\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Causal chain from GEXP15 loss to the transmission block not defined\", \"Which altered phosphorylation events drive the phenotype not established\", \"Essentiality not tested in P. falciparum\"],\n      \"attribution\": [{\"species\": \"Plasmodium berghei\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Confirming the RVxF-dependent PP1 interaction in P. falciparum and mapping a GYF-domain link to ribosomal/RNA-binding proteins extended the PP1-regulator model to the human pathogen and identified a second interaction interface.\",\n      \"evidence\": \"In vitro pull-down and phosphatase assays with recombinant proteins, Co-IP/MS, GYF-domain pull-down, live imaging, and in silico domain analysis in P. falciparum\",\n      \"pmids\": [\"37628837\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional consequence of GEXP15 binding ribosomal/RNA-binding proteins not tested\", \"Domain boundaries and the conserved domain of unknown function not experimentally validated\", \"How nuclear localization reconciles with the earlier exported/erythrocyte detection not addressed\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The physiological substrates and biological processes controlled by the GEXP15–PP1 complex, and how its ribosomal/RNA-binding and nuclear activities integrate with phosphatase regulation, remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No direct PP1 substrate assigned to GEXP15 regulation\", \"Mechanistic role of the GYF-domain ribosomal interaction unknown\", \"No structural model of the GEXP15–PP1 complex\"],\n      \"attribution\": [{\"species\": \"Plasmodium berghei\", \"strain\": \"\"}, {\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0008157\", \"supporting_discovery_ids\": [1, 2, 6]},\n      {\"term_id\": \"GO:0019888\", \"supporting_discovery_ids\": [2, 6]},\n      {\"term_id\": \"GO:0005515\", \"supporting_discovery_ids\": [1, 9]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [8]},\n      {\"term_id\": \"GO:0020007\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0035556\", \"supporting_discovery_ids\": [2, 5]},\n      {\"term_id\": \"GO:0030435\", \"supporting_discovery_ids\": [0, 4]}\n    ],\n    \"complexes\": [\n      \"GEXP15–PP1 complex\",\n      \"PP1-associated spliceosome-containing complex (P. berghei)\",\n      \"PP1-associated proteasome-containing complex (P. berghei)\",\n      \"GYF-domain ribosomal complex (P. falciparum)\"\n    ],\n    \"partners\": [\n      \"PP1 (PF3D7_1414400)\",\n      \"ribosomal proteins\",\n      \"RNA-binding proteins\"\n    ],\n    \"other_free_text\": [\n      \"N-terminal RVxF PP1-docking motif required for PP1 binding and activity enhancement [#2, #6]\",\n      \"GYF-like domain mediates binding to ribosomal complex [#7, #9]\",\n      \"Conserved domain of unknown function predicted but not experimentally characterized [#7]\",\n      \"N-terminal PEXEL/HT processing and N-acetylation detected in early gametocytes [#0]\",\n      \"Essential for asexual proliferation and mosquito transmission in P. berghei [#4]\"\n    ]\n  }\n}","audit_flag":null,"strains":[{"strain":"Pf3D7","gene_id":"PF3D7_1031600","name":null,"product":"protein GEXP15","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PbANKA","gene_id":"PBANKA_0515400","name":null,"product":"protein GEXP15","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PkH","gene_id":"PKNH_0616300","name":null,"product":"protein GEXP15, putative","uniprot_acc":null,"chromosome":null,"start_pos":null}],"gene_symbol":"GEXP15","evaluation":null}