{"gene":"PF3D7_1238900","run_date":"2026-09-08T14:19:06","timeline":{"discoveries":[{"year":1992,"finding":"PK2 (PfPK2) was identified as a putative serine/threonine protein kinase with a catalytic domain sharing homology with calcium-calmodulin-dependent protein kinase, protein kinase C, and cAMP-dependent protein kinase; it is expressed in a stage-specific fashion and localized primarily to the parasitic membrane, as determined by immunostaining with antiserum raised against a recombinant fragment expressed in E. coli.","method":"Molecular cloning, nucleotide/amino acid sequence analysis, recombinant protein expression in E. coli, immunostaining with specific antiserum","journal":"European journal of biochemistry","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — sequence-based homology plus direct immunolocalization, single lab, no in vitro kinase activity demonstrated in this study","pmids":["1378403"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2008,"finding":"PK2 (PfPK2) possesses intrinsic protein kinase activity that is Ca2+- and calmodulin-dependent: purified recombinant PfPK2 autophosphorylates and phosphorylates histone II(AS) as an exogenous substrate; this activity was abolished by replacement of the putative catalytic lysine with alanine and by calmodulin antagonists. PfPK2 was localized to merozoites and calmodulin antagonists markedly decreased ring-stage parasitemia in an invasion assay, implicating PfPK2 in erythrocyte invasion.","method":"Recombinant protein purification, in vitro kinase assay with [γ-32P]ATP, site-directed mutagenesis of catalytic lysine, phosphatase treatment, calmodulin antagonist inhibition, immunoelectron microscopy, in vitro invasion assay","journal":"Molecular and biochemical parasitology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro kinase assay with active-site mutagenesis and pharmacological validation; multiple orthogonal methods in a single focused study","pmids":["18762219"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2018,"finding":"Gene expression analysis showed that pk2 is upregulated during re-entry into the cell cycle following G1 arrest induced by polyamine depletion, and its expression is associated with deregulation of the pre-replicative complex, placing PK2 among Ca2+-sensitive kinases involved in cell cycle re-entry.","method":"Gene expression analysis (transcriptomics) following DFMO-induced G1 arrest and polyamine rescue","journal":"Scientific reports","confidence":"Low","confidence_rationale":"Tier 4 / Weak — expression-level correlation only; no direct functional or biochemical experiment on PK2 protein performed in this study","pmids":["30409996"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2023,"finding":"PK2 (PfPK2) is required for host erythrocyte invasion by P. falciparum merozoites: conditional knockdown of PfPK2 impairs invasion; PfPK2 regulates microneme protein secretion (including AMA1 release) necessary for tight-junction formation; comparative phosphoproteomics identified downstream substrates involved in invasion and signalling; PfPK2 acts upstream in cGMP-calcium signalling by regulating cGMP generation and calcium release, placing it as an upstream regulator of this second-messenger pathway critical for invasion.","method":"Conditional knockdown, invasion assays, AMA1 secretion assays, comparative phosphoproteomics, cGMP measurement, calcium release assays","journal":"PLoS pathogens","confidence":"High","confidence_rationale":"Tier 2 / Moderate — genetic loss-of-function with specific invasion phenotype, phosphoproteomic substrate identification, and second-messenger quantification; multiple orthogonal methods in a single focused study","pmids":["37988347"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]}],"current_model":"PK2 (PF3D7_1238900) is a Ca2+/calmodulin-dependent serine/threonine protein kinase localized to P. falciparum merozoites that is essential for erythrocyte invasion: its catalytic activity (defined by an active-site lysine) drives microneme protein (AMA1) secretion, tight-junction formation, and acts as an upstream regulator of cGMP generation and intracellular calcium release, placing PK2 at the apex of a cGMP-calcium signalling axis that orchestrates host-cell invasion."},"narrative":{"mechanistic_narrative":"PK2 (PF3D7_1238900) is a Ca2+/calmodulin-dependent serine/threonine protein kinase of P. falciparum that functions as an upstream orchestrator of merozoite invasion of host erythrocytes [PMID:18762219, PMID:37988347]. It was first identified as a putative serine/threonine kinase whose catalytic domain resembles calcium-calmodulin-dependent kinases, and is expressed in a stage-specific manner [PMID:1378403]. Recombinant PK2 autophosphorylates and phosphorylates an exogenous substrate in a Ca2+- and calmodulin-dependent manner, an activity abolished by mutation of its active-site catalytic lysine or by calmodulin antagonists, which also reduce parasite invasion [PMID:18762219]. Conditional knockdown establishes that PK2 is required for invasion: it drives microneme protein secretion including AMA1 release necessary for tight-junction formation, and acts upstream of the cGMP-calcium second-messenger axis by regulating cGMP generation and calcium release, with phosphoproteomics identifying downstream invasion and signalling substrates [PMID:37988347]. Beyond these findings, no further mechanistic detail—including direct in vivo substrates or the biochemical link between PK2 and cGMP synthesis—has been characterized in the available corpus.","teleology":[{"year":1992,"claim":"Establishing whether P. falciparum encodes a distinct calcium-regulated kinase, this work identified PK2 as a putative serine/threonine kinase and localized it to the parasitic membrane.","evidence":"Molecular cloning, sequence homology analysis, and immunostaining with antiserum against a recombinant fragment, in P. falciparum","pmids":["1378403"],"confidence":"Medium","gaps":["No in vitro kinase activity demonstrated in this study","Physiological substrates and cellular function undefined","Homology-based family assignment only, not biochemically validated"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2008,"claim":"Testing whether PK2 is a catalytically active, calcium-responsive kinase, this work demonstrated Ca2+/calmodulin-dependent autophosphorylation and substrate phosphorylation dependent on the active-site lysine, and linked its activity to invasion.","evidence":"Recombinant kinase assay with [γ-32P]ATP, catalytic-lysine mutagenesis, calmodulin-antagonist inhibition, immunoelectron microscopy, and in vitro invasion assay in P. falciparum merozoites","pmids":["18762219"],"confidence":"High","gaps":["Physiological substrates not identified in this study","Invasion link inferred from calmodulin antagonists, not direct PK2 loss-of-function","How Ca2+/calmodulin signals connect to invasion machinery unresolved"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2018,"claim":"Addressing when PK2 acts in the parasite cell cycle, transcriptomics placed pk2 among Ca2+-sensitive kinases upregulated during re-entry into the cycle after G1 arrest.","evidence":"Transcriptomic profiling following DFMO-induced G1 arrest and polyamine rescue in P. falciparum","pmids":["30409996"],"confidence":"Low","gaps":["Expression correlation only; no direct functional or biochemical assay on PK2 protein","Causal role of PK2 in cell-cycle re-entry not tested","Relationship between cell-cycle expression and invasion function unclear"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2023,"claim":"Resolving the in vivo role of PK2, genetic knockdown established it as essential for invasion through control of microneme (AMA1) secretion, tight-junction formation, and upstream regulation of the cGMP-calcium signalling axis.","evidence":"Conditional knockdown, invasion and AMA1 secretion assays, comparative phosphoproteomics, and cGMP/calcium measurements in P. falciparum","pmids":["37988347"],"confidence":"High","gaps":["Direct in vivo PK2 substrates among phosphoproteomic hits not individually validated","Biochemical mechanism by which PK2 regulates cGMP generation unknown","No structural model of PK2 or its complexes"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":null,"claim":"The direct molecular targets that connect PK2's kinase activity to cGMP synthesis and calcium release, and how these are spatially organized in the invading merozoite, remain undefined.","evidence":"","pmids":[],"confidence":"High","gaps":["No validated direct substrate linking PK2 to guanylyl cyclase or calcium channels","No reconstitution of the PK2-cGMP-calcium axis","No structural characterization of PK2"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]}],"mechanism_profile":{"molecular_activity":[],"localization":[],"pathway":[],"complexes":[],"partners":["CALMODULIN (ACTIVITY DEPENDENCE)","AMA1 (SECRETION REGULATED BY PK2)"],"other_free_text":["Ca2+/calmodulin-dependent kinase activity requires an intact active-site lysine [#1]","PK2 acts upstream in cGMP-calcium signalling during erythrocyte invasion [#3]","pk2 expression is upregulated during cell-cycle re-entry after G1 arrest [#2]"]}},"prefetch_data":{},"corpus_meta":[{"pmid":"1378403","id":"PMC_1378403","title":"Molecular cloning, stage-specific expression and cellular distribution of a putative protein kinase from Plasmodium falciparum.","date":"1992","source":"European journal of biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/1378403","citation_count":39,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["PfPK2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"30409996","id":"PMC_30409996","title":"Inducing controlled cell cycle arrest and re-entry during asexual proliferation of Plasmodium falciparum malaria parasites.","date":"2018","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/30409996","citation_count":35,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["PK2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"18762219","id":"PMC_18762219","title":"Characterization of Plasmodium falciparum protein kinase 2.","date":"2008","source":"Molecular and biochemical parasitology","url":"https://pubmed.ncbi.nlm.nih.gov/18762219","citation_count":20,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["protein kinase 2","PfPK2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"38491359","id":"PMC_38491359","title":"Microsatellites reveal high polymorphism and high potential for use in anti-malarial efficacy studies in areas with different transmission intensities in mainland Tanzania.","date":"2024","source":"Malaria journal","url":"https://pubmed.ncbi.nlm.nih.gov/38491359","citation_count":11,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["PfPK2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"16839657","id":"PMC_16839657","title":"A relevant in vitro eukaryotic live-cell system for the evaluation of plasmodial protein localization.","date":"2006","source":"Biochimie","url":"https://pubmed.ncbi.nlm.nih.gov/16839657","citation_count":7,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["PK2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"36307852","id":"PMC_36307852","title":"Molecular surveillance for anti-malarial drug resistance and genetic diversity of Plasmodium falciparum after chloroquine and sulfadoxine-pyrimethamine withdrawal in Quibdo, Colombia, 2018.","date":"2022","source":"Malaria journal","url":"https://pubmed.ncbi.nlm.nih.gov/36307852","citation_count":7,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["PfPK2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"37988347","id":"PMC_37988347","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":5,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["protein kinase 2","PfPK2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"39910229","id":"PMC_39910229","title":"Assessment of different genotyping markers and algorithms for distinguishing Plasmodium falciparum recrudescence from reinfection in Uganda.","date":"2025","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/39910229","citation_count":5,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["PfPK2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"39543779","id":"PMC_39543779","title":"Plasmodium falciparum genetic diversity and multiplicity of infection among asymptomatic and symptomatic malaria-infected individuals in Uganda.","date":"2024","source":"Tropical medicine and health","url":"https://pubmed.ncbi.nlm.nih.gov/39543779","citation_count":4,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["PfPK2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"39734236","id":"PMC_39734236","title":"Temporal changes in Plasmodium falciparum genetic diversity and multiplicity of infection across three areas of varying malaria transmission intensities in Uganda.","date":"2024","source":"Tropical medicine and health","url":"https://pubmed.ncbi.nlm.nih.gov/39734236","citation_count":1,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["PfPK2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"42270857","id":"PMC_42270857","title":"Comparison of techniques and markers to distinguish Plasmodium falciparum recrudescence from new infection in Rwanda.","date":"2026","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/42270857","citation_count":0,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["PfPK2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":9493,"output_tokens":1350,"usd":0.024365,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":6280,"output_tokens":2446,"usd":0.046275,"stage2_stop_reason":"end_turn"},"total_usd":0.07064,"stage1_batch_id":"msgbatch_011BPjN2BL33F8cJXD1r7V7T","stage2_batch_id":"msgbatch_01Qwg6vP7qxkpL6Gsc7tajsb","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1992,\n      \"finding\": \"PK2 (PfPK2) was identified as a putative serine/threonine protein kinase with a catalytic domain sharing homology with calcium-calmodulin-dependent protein kinase, protein kinase C, and cAMP-dependent protein kinase; it is expressed in a stage-specific fashion and localized primarily to the parasitic membrane, as determined by immunostaining with antiserum raised against a recombinant fragment expressed in E. coli.\",\n      \"method\": \"Molecular cloning, nucleotide/amino acid sequence analysis, recombinant protein expression in E. coli, immunostaining with specific antiserum\",\n      \"journal\": \"European journal of biochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — sequence-based homology plus direct immunolocalization, single lab, no in vitro kinase activity demonstrated in this study\",\n      \"pmids\": [\"1378403\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"PK2 (PfPK2) possesses intrinsic protein kinase activity that is Ca2+- and calmodulin-dependent: purified recombinant PfPK2 autophosphorylates and phosphorylates histone II(AS) as an exogenous substrate; this activity was abolished by replacement of the putative catalytic lysine with alanine and by calmodulin antagonists. PfPK2 was localized to merozoites and calmodulin antagonists markedly decreased ring-stage parasitemia in an invasion assay, implicating PfPK2 in erythrocyte invasion.\",\n      \"method\": \"Recombinant protein purification, in vitro kinase assay with [γ-32P]ATP, site-directed mutagenesis of catalytic lysine, phosphatase treatment, calmodulin antagonist inhibition, immunoelectron microscopy, in vitro invasion assay\",\n      \"journal\": \"Molecular and biochemical parasitology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro kinase assay with active-site mutagenesis and pharmacological validation; multiple orthogonal methods in a single focused study\",\n      \"pmids\": [\"18762219\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Gene expression analysis showed that pk2 is upregulated during re-entry into the cell cycle following G1 arrest induced by polyamine depletion, and its expression is associated with deregulation of the pre-replicative complex, placing PK2 among Ca2+-sensitive kinases involved in cell cycle re-entry.\",\n      \"method\": \"Gene expression analysis (transcriptomics) following DFMO-induced G1 arrest and polyamine rescue\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 4 / Weak — expression-level correlation only; no direct functional or biochemical experiment on PK2 protein performed in this study\",\n      \"pmids\": [\"30409996\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"PK2 (PfPK2) is required for host erythrocyte invasion by P. falciparum merozoites: conditional knockdown of PfPK2 impairs invasion; PfPK2 regulates microneme protein secretion (including AMA1 release) necessary for tight-junction formation; comparative phosphoproteomics identified downstream substrates involved in invasion and signalling; PfPK2 acts upstream in cGMP-calcium signalling by regulating cGMP generation and calcium release, placing it as an upstream regulator of this second-messenger pathway critical for invasion.\",\n      \"method\": \"Conditional knockdown, invasion assays, AMA1 secretion assays, comparative phosphoproteomics, cGMP measurement, calcium release assays\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic loss-of-function with specific invasion phenotype, phosphoproteomic substrate identification, and second-messenger quantification; multiple orthogonal methods in a single focused study\",\n      \"pmids\": [\"37988347\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    }\n  ],\n  \"current_model\": \"PK2 (PF3D7_1238900) is a Ca2+/calmodulin-dependent serine/threonine protein kinase localized to P. falciparum merozoites that is essential for erythrocyte invasion: its catalytic activity (defined by an active-site lysine) drives microneme protein (AMA1) secretion, tight-junction formation, and acts as an upstream regulator of cGMP generation and intracellular calcium release, placing PK2 at the apex of a cGMP-calcium signalling axis that orchestrates host-cell invasion.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"PK2 (PF3D7_1238900) is a Ca2+/calmodulin-dependent serine/threonine protein kinase of P. falciparum that functions as an upstream orchestrator of merozoite invasion of host erythrocytes [#1, #3]. It was first identified as a putative serine/threonine kinase whose catalytic domain resembles calcium-calmodulin-dependent kinases, and is expressed in a stage-specific manner [#0]. Recombinant PK2 autophosphorylates and phosphorylates an exogenous substrate in a Ca2+- and calmodulin-dependent manner, an activity abolished by mutation of its active-site catalytic lysine or by calmodulin antagonists, which also reduce parasite invasion [#1]. Conditional knockdown establishes that PK2 is required for invasion: it drives microneme protein secretion including AMA1 release necessary for tight-junction formation, and acts upstream of the cGMP-calcium second-messenger axis by regulating cGMP generation and calcium release, with phosphoproteomics identifying downstream invasion and signalling substrates [#3]. Beyond these findings, no further mechanistic detail—including direct in vivo substrates or the biochemical link between PK2 and cGMP synthesis—has been characterized in the available corpus.\",\n  \"teleology\": [\n    {\n      \"year\": 1992,\n      \"claim\": \"Establishing whether P. falciparum encodes a distinct calcium-regulated kinase, this work identified PK2 as a putative serine/threonine kinase and localized it to the parasitic membrane.\",\n      \"evidence\": \"Molecular cloning, sequence homology analysis, and immunostaining with antiserum against a recombinant fragment, in P. falciparum\",\n      \"pmids\": [\"1378403\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"No in vitro kinase activity demonstrated in this study\",\n        \"Physiological substrates and cellular function undefined\",\n        \"Homology-based family assignment only, not biochemically validated\"\n      ],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Testing whether PK2 is a catalytically active, calcium-responsive kinase, this work demonstrated Ca2+/calmodulin-dependent autophosphorylation and substrate phosphorylation dependent on the active-site lysine, and linked its activity to invasion.\",\n      \"evidence\": \"Recombinant kinase assay with [\\u03b3-32P]ATP, catalytic-lysine mutagenesis, calmodulin-antagonist inhibition, immunoelectron microscopy, and in vitro invasion assay in P. falciparum merozoites\",\n      \"pmids\": [\"18762219\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Physiological substrates not identified in this study\",\n        \"Invasion link inferred from calmodulin antagonists, not direct PK2 loss-of-function\",\n        \"How Ca2+/calmodulin signals connect to invasion machinery unresolved\"\n      ],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Addressing when PK2 acts in the parasite cell cycle, transcriptomics placed pk2 among Ca2+-sensitive kinases upregulated during re-entry into the cycle after G1 arrest.\",\n      \"evidence\": \"Transcriptomic profiling following DFMO-induced G1 arrest and polyamine rescue in P. falciparum\",\n      \"pmids\": [\"30409996\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"Expression correlation only; no direct functional or biochemical assay on PK2 protein\",\n        \"Causal role of PK2 in cell-cycle re-entry not tested\",\n        \"Relationship between cell-cycle expression and invasion function unclear\"\n      ],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Resolving the in vivo role of PK2, genetic knockdown established it as essential for invasion through control of microneme (AMA1) secretion, tight-junction formation, and upstream regulation of the cGMP-calcium signalling axis.\",\n      \"evidence\": \"Conditional knockdown, invasion and AMA1 secretion assays, comparative phosphoproteomics, and cGMP/calcium measurements in P. falciparum\",\n      \"pmids\": [\"37988347\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Direct in vivo PK2 substrates among phosphoproteomic hits not individually validated\",\n        \"Biochemical mechanism by which PK2 regulates cGMP generation unknown\",\n        \"No structural model of PK2 or its complexes\"\n      ],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The direct molecular targets that connect PK2's kinase activity to cGMP synthesis and calcium release, and how these are spatially organized in the invading merozoite, remain undefined.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"No validated direct substrate linking PK2 to guanylyl cyclase or calcium channels\",\n        \"No reconstitution of the PK2-cGMP-calcium axis\",\n        \"No structural characterization of PK2\"\n      ],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0004674\", \"supporting_discovery_ids\": [0, 1, 3]},\n      {\"term_id\": \"GO:0004683\", \"supporting_discovery_ids\": [1]},\n      {\"term_id\": \"GO:0046777\", \"supporting_discovery_ids\": [1]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0020009\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"GO:0016020\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0044409\", \"supporting_discovery_ids\": [1, 3]},\n      {\"term_id\": \"GO:0006816\", \"supporting_discovery_ids\": [3]},\n      {\"term_id\": \"GO:0035556\", \"supporting_discovery_ids\": [3]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"Calmodulin (activity dependence)\",\n      \"AMA1 (secretion regulated by PK2)\"\n    ],\n    \"other_free_text\": [\n      \"Ca2+/calmodulin-dependent kinase activity requires an intact active-site lysine [#1]\",\n      \"PK2 acts upstream in cGMP-calcium signalling during erythrocyte invasion [#3]\",\n      \"pk2 expression is upregulated during cell-cycle re-entry after G1 arrest [#2]\"\n    ]\n  }\n}","audit_flag":null,"strains":[{"strain":"Pf3D7","gene_id":"PF3D7_1238900","name":null,"product":"protein kinase 2","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PbANKA","gene_id":"PBANKA_1453400","name":null,"product":"protein kinase 2","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PkH","gene_id":"PKNH_1458700","name":null,"product":"serine/threonine protein kinase, putative","uniprot_acc":null,"chromosome":null,"start_pos":null}],"gene_symbol":"PK2","evaluation":null}