{"gene":"PF3D7_0312400","run_date":"2026-09-07T10:55:51","timeline":{"discoveries":[{"year":2004,"finding":"Recombinant PfGSK-3beta (PF3D7_0312400) phosphorylates GS-1 (a GSK-3-specific peptide substrate), glycogen synthase, recombinant axin, and the microtubule-binding protein tau in vitro, demonstrating its kinase activity and substrate range.","method":"In vitro kinase assay with recombinant protein and defined substrates","journal":"Biochimica et biophysica acta","confidence":"High","confidence_rationale":"Tier 1 / Moderate — direct in vitro enzymatic assay with multiple substrates, single lab but multiple orthogonal substrate tests","pmids":["15023360"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2004,"finding":"Neither native nor recombinant PfGSK-3beta binds to axin, a result that distinguishes the parasite enzyme from mammalian GSK-3beta.","method":"Binding assay (pulldown/interaction assay) with recombinant proteins","journal":"Biochimica et biophysica acta","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — direct binding experiment, single lab, negative result","pmids":["15023360"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2004,"finding":"PfGSK-3beta protein is predominantly expressed at the early trophozoite stage in erythrocytic stages, despite mRNA being present at similar amounts at all stages, and the protein is rapidly transported to the erythrocyte cytoplasm where it associates with vesicle-like structures.","method":"Western blot for protein expression across stages; immunofluorescence/localization for subcellular distribution","journal":"Biochimica et biophysica acta","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — direct localization by immunostaining and stage-specific protein expression by western blot, single lab","pmids":["15023360"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2004,"finding":"A homology model of PfGSK-3beta based on the crystal structure of human GSK-3beta showed that the active site, P+4 phosphate binding domain (substrate binding), and activity regulation regions are highly conserved between the parasite and human enzymes.","method":"3D homology modeling based on human GSK-3beta crystal structure","journal":"Biochimica et biophysica acta","confidence":"Low","confidence_rationale":"Tier 4 / Weak — computational model only, no experimental structural validation","pmids":["15023360"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2004,"finding":"GSK-3beta inhibitors tested on both PfGSK-3beta and mammalian GSK-3beta showed partially divergent sensitivity, indicating the enzymes have distinguishable inhibitor profiles that could enable selective inhibitor development.","method":"In vitro kinase inhibition assays comparing recombinant PfGSK-3beta and mammalian GSK-3beta with a panel of inhibitors","journal":"Biochimica et biophysica acta","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — direct comparative enzymatic assay with multiple inhibitors, single lab","pmids":["15023360"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2016,"finding":"PfGSK-3beta (GSK3) phosphorylates a conserved threonine residue (T613) in the cytoplasmic domain of Apical Membrane Antigen 1 (AMA1) in vitro, but only after PKA-mediated priming phosphorylation at S610; both phosphorylation steps are required for efficient erythrocyte invasion.","method":"In vitro kinase assay; epistasis established by sequential phosphorylation experiments and functional invasion assays","journal":"Scientific reports","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution of hierarchical phosphorylation with defined substrates and mutagenesis, functional invasion assay, single lab but multiple orthogonal methods","pmids":["27698395"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2012,"finding":"3,6-Diamino-4-(2-halophenyl)-2-benzoylthieno[2,3-b]pyridine-5-carbonitriles selectively inhibit recombinant PfGSK-3beta over human GSK-3beta in vitro, and subtle differences in the ATP-binding pockets of the two enzymes account for the observed selectivity.","method":"In vitro kinase inhibition assay with recombinant PfGSK-3beta; X-ray structure of related molecule in complex with human GSK-3beta used for comparative modeling","journal":"Journal of medicinal chemistry","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — direct enzymatic assay with recombinant enzyme plus structural comparison, single lab","pmids":["23214499"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2022,"finding":"Targeted gene disruption of PfGSK-3beta (the active gene copy among two GSK3 copies in P. falciparum) is not lethal for asexual blood stage proliferation but reduces erythrocyte invasion efficiency by ~69%, as confirmed by rescue experiments with wildtype and catalytically inactive mutants; functional knockout does not transcriptionally upregulate the second PfGSK3 copy.","method":"Targeted gene disruption (reverse genetics); growth assays; rescue with wildtype and catalytically inactive mutants","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Moderate — genetic knockout with defined phenotypic readout, confirmed by rescue with wildtype and catalytic mutant, single lab but multiple orthogonal lines of evidence","pmids":["35961464"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2022,"finding":"PfGSK-3beta-deficient gametocytes display strikingly malformed morphology and die in later stages of gametocyte development, demonstrating that PfGSK-3beta is required for gametocyte maturation.","method":"Conditional gene inactivation during gametocytogenesis; morphological analysis and viability assessment","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Moderate — conditional genetic inactivation with defined morphological and viability phenotype, single lab","pmids":["35961464"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2022,"finding":"The unconventional N-terminal region of PfGSK-3beta contains autophosphorylation sites; N-terminal phosphorylation promotes increased kinase activity by inducing conformational changes in the N-terminus, as shown by combining molecular modeling with experimental small-angle X-ray scattering (SAXS) data.","method":"Autophosphorylation mapping; small-angle X-ray scattering (SAXS); molecular modeling","journal":"The Biochemical journal","confidence":"High","confidence_rationale":"Tier 1 / Moderate — experimental SAXS structural data combined with autophosphorylation assay and modeling, single lab but multiple orthogonal methods","pmids":["35023554"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]}],"current_model":"PfGSK-3beta (PF3D7_0312400) is a catalytically active serine/threonine kinase that phosphorylates substrates including GSK-3-specific peptides, glycogen synthase, tau, and the invasion ligand AMA1 (T613) after PKA-mediated priming at S610; its activity is positively regulated by autophosphorylation of an unconventional N-terminal extension that induces activating conformational changes; it localises to vesicle-like structures in the erythrocyte cytoplasm predominantly at the trophozoite stage; it is dispensable for asexual blood-stage survival but required for efficient erythrocyte invasion and essential for gametocyte maturation."},"narrative":{"mechanistic_narrative":"PfGSK-3beta (PF3D7_0312400) is a catalytically active serine/threonine kinase of Plasmodium falciparum that couples protein phosphorylation to the parasite's erythrocytic and sexual development [PMID:15023360, PMID:35961464]. Recombinant enzyme phosphorylates GSK-3-specific peptide substrates, glycogen synthase, and tau, establishing its intrinsic kinase activity and substrate range [PMID:15023360]. Functionally, it acts within an invasion-associated phosphorylation hierarchy: it phosphorylates threonine 613 in the cytoplasmic domain of the invasion ligand AMA1, but only after PKA-mediated priming at S610, and both steps are required for efficient erythrocyte invasion [PMID:27698395]. Its own activity is positively regulated by autophosphorylation of an unconventional N-terminal extension, which induces activating conformational changes detected by SAXS [PMID:35023554]. The enzyme is predominantly expressed at the early trophozoite stage and is exported to the erythrocyte cytoplasm where it associates with vesicle-like structures [PMID:15023360]. Genetically, PfGSK-3beta is dispensable for asexual blood-stage proliferation but its disruption reduces erythrocyte invasion by ~69% [PMID:35961464], while conditional inactivation causes malformed gametocytes and death in late gametocytogenesis, making it essential for gametocyte maturation [PMID:35961464]. It is pharmacologically distinguishable from human GSK-3beta through subtle ATP-pocket differences that permit selective inhibitors [PMID:15023360, PMID:23214499], and unlike mammalian GSK-3beta it does not bind axin [PMID:15023360].","teleology":[{"year":2004,"claim":"Establishing that the parasite gene encodes a functional kinase was the first requirement; in vitro assays showed PfGSK-3beta phosphorylates canonical GSK-3 substrates, confirming conserved catalytic identity.","evidence":"In vitro kinase assay with recombinant protein against GS-1 peptide, glycogen synthase, axin, and tau","pmids":["15023360"],"confidence":"High","gaps":["No physiological parasite substrate identified at this stage","Substrate range shown in vitro does not establish in vivo targets"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2004,"claim":"Whether the parasite enzyme behaves like mammalian GSK-3beta mattered for both biology and drug targeting; a binding assay showed PfGSK-3beta does not bind axin, and stage-specific analysis placed the protein in the erythrocyte cytoplasm at the trophozoite stage.","evidence":"Pulldown/binding assay for axin; western blot across stages and immunofluorescence localization","pmids":["15023360"],"confidence":"Medium","gaps":["Function of vesicle-like localization unresolved","Basis for post-transcriptional stage-specific protein accumulation not defined"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2012,"claim":"To exploit the enzyme therapeutically, its druggability relative to the human ortholog was tested; thienopyridine carbonitriles selectively inhibited PfGSK-3beta, attributed to ATP-pocket differences.","evidence":"In vitro kinase inhibition assay with recombinant PfGSK-3beta and comparative structural modeling against human GSK-3beta","pmids":["23214499"],"confidence":"Medium","gaps":["Selectivity shown biochemically, not confirmed against parasites","No co-crystal structure of PfGSK-3beta with inhibitor"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2016,"claim":"A physiological substrate and pathway context were unknown; reconstitution showed PfGSK-3beta phosphorylates AMA1 T613 only after PKA priming at S610, defining a hierarchical phosphorylation event required for invasion.","evidence":"Sequential in vitro kinase assays with defined substrates, mutagenesis, and functional erythrocyte invasion assays","pmids":["27698395"],"confidence":"High","gaps":["Direct evidence that PfGSK-3beta phosphorylates AMA1 in vivo during invasion not established","Other physiological substrates unknown"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2022,"claim":"How the enzyme's own activity is controlled was unclear; mapping identified autophosphorylation sites in an unconventional N-terminal extension that drive activating conformational changes.","evidence":"Autophosphorylation site mapping combined with SAXS and molecular modeling","pmids":["35023554"],"confidence":"High","gaps":["Upstream trigger for autophosphorylation not identified","In vivo relevance of the conformational switch not tested"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2022,"claim":"The essentiality and stage-specific requirement were resolved genetically; disruption spares asexual proliferation but reduces invasion ~69% and, via conditional inactivation, blocks gametocyte maturation.","evidence":"Targeted gene disruption with wildtype and catalytic-mutant rescue, growth/invasion assays, and conditional inactivation during gametocytogenesis with morphological analysis","pmids":["35961464"],"confidence":"High","gaps":["Molecular substrates underlying the gametocyte maturation defect not identified","Whether the second PfGSK3 copy has any compensatory role remains untested beyond transcription"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":null,"claim":"The full physiological substrate repertoire and the signaling inputs that control PfGSK-3beta activity during invasion and gametocytogenesis remain undefined.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unbiased in vivo phosphoproteomic substrate map","Link between vesicular localization and invasion function unresolved","Mechanism connecting kinase activity to gametocyte morphology unknown"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]}],"mechanism_profile":{"molecular_activity":[],"localization":[],"pathway":[],"complexes":[],"partners":["AMA1 (SUBSTRATE, PHOSPHORYLATED AT T613 AFTER PKA PRIMING) [#5]","PKA (PRIMING KINASE UPSTREAM OF PFGSK-3BETA IN AMA1 PHOSPHORYLATION) [#5]"],"other_free_text":["Does not bind axin, distinguishing it from mammalian GSK-3beta [#1]","Predominantly expressed at early trophozoite stage despite constant mRNA levels [#2]","Pharmacologically selectable over human GSK-3beta via ATP-pocket differences [#4, #6]","One of two GSK3 copies in P. falciparum; it is the active copy and the second copy is not transcriptionally upregulated on its disruption [#7]"]}},"prefetch_data":{},"corpus_meta":[{"pmid":"15479470","id":"PMC_15479470","title":"Protein kinases of the human malaria parasite Plasmodium falciparum: the kinome of a divergent eukaryote.","date":"2004","source":"BMC genomics","url":"https://pubmed.ncbi.nlm.nih.gov/15479470","citation_count":421,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["curated_ref"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"15023360","id":"PMC_15023360","title":"Plasmodium falciparum glycogen synthase kinase-3: molecular model, expression, intracellular localisation and selective inhibitors.","date":"2004","source":"Biochimica et biophysica 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3"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":20132,"output_tokens":2503,"usd":0.048971,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":7972,"output_tokens":2896,"usd":0.05613,"stage2_stop_reason":"end_turn"},"total_usd":0.105101,"stage1_batch_id":"msgbatch_01DbiymDmubkPpYvdbAu5a7V","stage2_batch_id":"msgbatch_012TbrWvMRH129T7PQ4SmvrJ","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2004,\n      \"finding\": \"Recombinant PfGSK-3beta (PF3D7_0312400) phosphorylates GS-1 (a GSK-3-specific peptide substrate), glycogen synthase, recombinant axin, and the microtubule-binding protein tau in vitro, demonstrating its kinase activity and substrate range.\",\n      \"method\": \"In vitro kinase assay with recombinant protein and defined substrates\",\n      \"journal\": \"Biochimica et biophysica acta\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — direct in vitro enzymatic assay with multiple substrates, single lab but multiple orthogonal substrate tests\",\n      \"pmids\": [\"15023360\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Neither native nor recombinant PfGSK-3beta binds to axin, a result that distinguishes the parasite enzyme from mammalian GSK-3beta.\",\n      \"method\": \"Binding assay (pulldown/interaction assay) with recombinant proteins\",\n      \"journal\": \"Biochimica et biophysica acta\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — direct binding experiment, single lab, negative result\",\n      \"pmids\": [\"15023360\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"PfGSK-3beta protein is predominantly expressed at the early trophozoite stage in erythrocytic stages, despite mRNA being present at similar amounts at all stages, and the protein is rapidly transported to the erythrocyte cytoplasm where it associates with vesicle-like structures.\",\n      \"method\": \"Western blot for protein expression across stages; immunofluorescence/localization for subcellular distribution\",\n      \"journal\": \"Biochimica et biophysica acta\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — direct localization by immunostaining and stage-specific protein expression by western blot, single lab\",\n      \"pmids\": [\"15023360\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"A homology model of PfGSK-3beta based on the crystal structure of human GSK-3beta showed that the active site, P+4 phosphate binding domain (substrate binding), and activity regulation regions are highly conserved between the parasite and human enzymes.\",\n      \"method\": \"3D homology modeling based on human GSK-3beta crystal structure\",\n      \"journal\": \"Biochimica et biophysica acta\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 4 / Weak — computational model only, no experimental structural validation\",\n      \"pmids\": [\"15023360\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"GSK-3beta inhibitors tested on both PfGSK-3beta and mammalian GSK-3beta showed partially divergent sensitivity, indicating the enzymes have distinguishable inhibitor profiles that could enable selective inhibitor development.\",\n      \"method\": \"In vitro kinase inhibition assays comparing recombinant PfGSK-3beta and mammalian GSK-3beta with a panel of inhibitors\",\n      \"journal\": \"Biochimica et biophysica acta\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — direct comparative enzymatic assay with multiple inhibitors, single lab\",\n      \"pmids\": [\"15023360\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"PfGSK-3beta (GSK3) phosphorylates a conserved threonine residue (T613) in the cytoplasmic domain of Apical Membrane Antigen 1 (AMA1) in vitro, but only after PKA-mediated priming phosphorylation at S610; both phosphorylation steps are required for efficient erythrocyte invasion.\",\n      \"method\": \"In vitro kinase assay; epistasis established by sequential phosphorylation experiments and functional invasion assays\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution of hierarchical phosphorylation with defined substrates and mutagenesis, functional invasion assay, single lab but multiple orthogonal methods\",\n      \"pmids\": [\"27698395\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"3,6-Diamino-4-(2-halophenyl)-2-benzoylthieno[2,3-b]pyridine-5-carbonitriles selectively inhibit recombinant PfGSK-3beta over human GSK-3beta in vitro, and subtle differences in the ATP-binding pockets of the two enzymes account for the observed selectivity.\",\n      \"method\": \"In vitro kinase inhibition assay with recombinant PfGSK-3beta; X-ray structure of related molecule in complex with human GSK-3beta used for comparative modeling\",\n      \"journal\": \"Journal of medicinal chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — direct enzymatic assay with recombinant enzyme plus structural comparison, single lab\",\n      \"pmids\": [\"23214499\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Targeted gene disruption of PfGSK-3beta (the active gene copy among two GSK3 copies in P. falciparum) is not lethal for asexual blood stage proliferation but reduces erythrocyte invasion efficiency by ~69%, as confirmed by rescue experiments with wildtype and catalytically inactive mutants; functional knockout does not transcriptionally upregulate the second PfGSK3 copy.\",\n      \"method\": \"Targeted gene disruption (reverse genetics); growth assays; rescue with wildtype and catalytically inactive mutants\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic knockout with defined phenotypic readout, confirmed by rescue with wildtype and catalytic mutant, single lab but multiple orthogonal lines of evidence\",\n      \"pmids\": [\"35961464\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"PfGSK-3beta-deficient gametocytes display strikingly malformed morphology and die in later stages of gametocyte development, demonstrating that PfGSK-3beta is required for gametocyte maturation.\",\n      \"method\": \"Conditional gene inactivation during gametocytogenesis; morphological analysis and viability assessment\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — conditional genetic inactivation with defined morphological and viability phenotype, single lab\",\n      \"pmids\": [\"35961464\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"The unconventional N-terminal region of PfGSK-3beta contains autophosphorylation sites; N-terminal phosphorylation promotes increased kinase activity by inducing conformational changes in the N-terminus, as shown by combining molecular modeling with experimental small-angle X-ray scattering (SAXS) data.\",\n      \"method\": \"Autophosphorylation mapping; small-angle X-ray scattering (SAXS); molecular modeling\",\n      \"journal\": \"The Biochemical journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — experimental SAXS structural data combined with autophosphorylation assay and modeling, single lab but multiple orthogonal methods\",\n      \"pmids\": [\"35023554\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    }\n  ],\n  \"current_model\": \"PfGSK-3beta (PF3D7_0312400) is a catalytically active serine/threonine kinase that phosphorylates substrates including GSK-3-specific peptides, glycogen synthase, tau, and the invasion ligand AMA1 (T613) after PKA-mediated priming at S610; its activity is positively regulated by autophosphorylation of an unconventional N-terminal extension that induces activating conformational changes; it localises to vesicle-like structures in the erythrocyte cytoplasm predominantly at the trophozoite stage; it is dispensable for asexual blood-stage survival but required for efficient erythrocyte invasion and essential for gametocyte maturation.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"PfGSK-3beta (PF3D7_0312400) is a catalytically active serine/threonine kinase of Plasmodium falciparum that couples protein phosphorylation to the parasite's erythrocytic and sexual development [#0, #7]. Recombinant enzyme phosphorylates GSK-3-specific peptide substrates, glycogen synthase, and tau, establishing its intrinsic kinase activity and substrate range [#0]. Functionally, it acts within an invasion-associated phosphorylation hierarchy: it phosphorylates threonine 613 in the cytoplasmic domain of the invasion ligand AMA1, but only after PKA-mediated priming at S610, and both steps are required for efficient erythrocyte invasion [#5]. Its own activity is positively regulated by autophosphorylation of an unconventional N-terminal extension, which induces activating conformational changes detected by SAXS [#9]. The enzyme is predominantly expressed at the early trophozoite stage and is exported to the erythrocyte cytoplasm where it associates with vesicle-like structures [#2]. Genetically, PfGSK-3beta is dispensable for asexual blood-stage proliferation but its disruption reduces erythrocyte invasion by ~69% [#7], while conditional inactivation causes malformed gametocytes and death in late gametocytogenesis, making it essential for gametocyte maturation [#8]. It is pharmacologically distinguishable from human GSK-3beta through subtle ATP-pocket differences that permit selective inhibitors [#4, #6], and unlike mammalian GSK-3beta it does not bind axin [#1].\",\n  \"teleology\": [\n    {\n      \"year\": 2004,\n      \"claim\": \"Establishing that the parasite gene encodes a functional kinase was the first requirement; in vitro assays showed PfGSK-3beta phosphorylates canonical GSK-3 substrates, confirming conserved catalytic identity.\",\n      \"evidence\": \"In vitro kinase assay with recombinant protein against GS-1 peptide, glycogen synthase, axin, and tau\",\n      \"pmids\": [\"15023360\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No physiological parasite substrate identified at this stage\", \"Substrate range shown in vitro does not establish in vivo targets\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Whether the parasite enzyme behaves like mammalian GSK-3beta mattered for both biology and drug targeting; a binding assay showed PfGSK-3beta does not bind axin, and stage-specific analysis placed the protein in the erythrocyte cytoplasm at the trophozoite stage.\",\n      \"evidence\": \"Pulldown/binding assay for axin; western blot across stages and immunofluorescence localization\",\n      \"pmids\": [\"15023360\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Function of vesicle-like localization unresolved\", \"Basis for post-transcriptional stage-specific protein accumulation not defined\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"To exploit the enzyme therapeutically, its druggability relative to the human ortholog was tested; thienopyridine carbonitriles selectively inhibited PfGSK-3beta, attributed to ATP-pocket differences.\",\n      \"evidence\": \"In vitro kinase inhibition assay with recombinant PfGSK-3beta and comparative structural modeling against human GSK-3beta\",\n      \"pmids\": [\"23214499\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Selectivity shown biochemically, not confirmed against parasites\", \"No co-crystal structure of PfGSK-3beta with inhibitor\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"A physiological substrate and pathway context were unknown; reconstitution showed PfGSK-3beta phosphorylates AMA1 T613 only after PKA priming at S610, defining a hierarchical phosphorylation event required for invasion.\",\n      \"evidence\": \"Sequential in vitro kinase assays with defined substrates, mutagenesis, and functional erythrocyte invasion assays\",\n      \"pmids\": [\"27698395\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct evidence that PfGSK-3beta phosphorylates AMA1 in vivo during invasion not established\", \"Other physiological substrates unknown\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"How the enzyme's own activity is controlled was unclear; mapping identified autophosphorylation sites in an unconventional N-terminal extension that drive activating conformational changes.\",\n      \"evidence\": \"Autophosphorylation site mapping combined with SAXS and molecular modeling\",\n      \"pmids\": [\"35023554\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Upstream trigger for autophosphorylation not identified\", \"In vivo relevance of the conformational switch not tested\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"The essentiality and stage-specific requirement were resolved genetically; disruption spares asexual proliferation but reduces invasion ~69% and, via conditional inactivation, blocks gametocyte maturation.\",\n      \"evidence\": \"Targeted gene disruption with wildtype and catalytic-mutant rescue, growth/invasion assays, and conditional inactivation during gametocytogenesis with morphological analysis\",\n      \"pmids\": [\"35961464\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular substrates underlying the gametocyte maturation defect not identified\", \"Whether the second PfGSK3 copy has any compensatory role remains untested beyond transcription\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The full physiological substrate repertoire and the signaling inputs that control PfGSK-3beta activity during invasion and gametocytogenesis remain undefined.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unbiased in vivo phosphoproteomic substrate map\", \"Link between vesicular localization and invasion function unresolved\", \"Mechanism connecting kinase activity to gametocyte morphology unknown\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0004674\", \"supporting_discovery_ids\": [0, 5, 9]},\n      {\"term_id\": \"GO:0046777\", \"supporting_discovery_ids\": [9]},\n      {\"term_id\": \"GO:0005524\", \"supporting_discovery_ids\": [6]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0020030\", \"supporting_discovery_ids\": [2]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0007155\", \"supporting_discovery_ids\": [5, 7]},\n      {\"term_id\": \"GO:0030154\", \"supporting_discovery_ids\": [8]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"AMA1 (substrate, phosphorylated at T613 after PKA priming) [#5]\",\n      \"PKA (priming kinase upstream of PfGSK-3beta in AMA1 phosphorylation) [#5]\"\n    ],\n    \"other_free_text\": [\n      \"Does not bind axin, distinguishing it from mammalian GSK-3beta [#1]\",\n      \"Predominantly expressed at early trophozoite stage despite constant mRNA levels [#2]\",\n      \"Pharmacologically selectable over human GSK-3beta via ATP-pocket differences [#4, #6]\",\n      \"One of two GSK3 copies in P. falciparum; it is the active copy and the second copy is not transcriptionally upregulated on its disruption [#7]\"\n    ]\n  }\n}","audit_flag":null,"strains":[{"strain":"Pf3D7","gene_id":"PF3D7_0312400","name":null,"product":"glycogen synthase kinase-3 beta","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PbANKA","gene_id":"PBANKA_0410400","name":null,"product":"glycogen synthase kinase 3, putative","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PkH","gene_id":"PKNH_0829800","name":null,"product":"glycogen synthase kinase-3 beta, putative","uniprot_acc":null,"chromosome":null,"start_pos":null}],"gene_symbol":"GSK3beta","evaluation":null}