{"gene":"PF3D7_1223100","run_date":"2026-09-08T14:19:06","timeline":{"discoveries":[{"year":2008,"finding":"Recombinant PKAr (PfPKA-R) added to the patch-clamp pipette in vitro, or overexpressed in transgenic P. falciparum parasites, down-regulates anion conductance of the infected erythrocyte membrane, demonstrating that PKAr negatively modulates the New Permeation Pathway anion channel in a cAMP-dependent manner. The growth defect caused by PKAr overexpression was restored by increasing intracellular cAMP levels, consistent with PKAr sequestering the catalytic subunit.","method":"Patch-clamp electrophysiology on infected erythrocytes with recombinant protein addition; transgenic parasite overexpression; cAMP rescue assay","journal":"PLoS pathogens","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal functional assays (in vitro patch-clamp with recombinant protein plus transgenic overexpression in parasite) with pharmacological rescue, single lab but two orthogonal methods","pmids":["18248092"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2016,"finding":"The crystal structure of PKAr in complex with cAMP and the antimalarial analogue (Sp)-2-Cl-cAMPS was solved, revealing that PKAr holds the catalytic subunit (PKA-C) in an inactive state through allosteric inhibition, and that binding of two cAMP molecules stabilizes a conformation that releases PKA-C to phosphorylate downstream substrates such as apical membrane antigen 1 (AMA1).","method":"X-ray crystallography of PKAr–cAMP and PKAr–(Sp)-2-Cl-cAMPS complexes; functional assays with membrane-permeable cAMP agonists on parasite growth","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — crystal structure with functional validation (agonist-induced growth disruption), single lab with structural and cell-based methods","pmids":["27738107"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2020,"finding":"PKAr undergoes Ca2+-dependent phosphorylation in P. falciparum merozoites upon transition from high-K+ to low-K+ ionic environments. Phosphorylated PKAr is bound by Pf14-3-3I, demonstrated by co-immunoprecipitation and gel filtration chromatography, assembling a multiprotein signaling complex. A phospho-peptide mimicking PKAr Ca2+-dependent phosphosites (P1) binds Pf14-3-3I, disrupts this complex, and inhibits microneme secretion and RBC invasion.","method":"Quantitative phosphoproteomics; co-immunoprecipitation; gel filtration chromatography; phospho-peptide competition assay; microneme secretion and invasion assays","journal":"mBio","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP plus gel filtration plus phosphoproteomic identification plus functional peptide disruption assay, single lab with multiple orthogonal methods","pmids":["32817103"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2019,"finding":"Phosphoproteomic analysis of PDEβ-null P. falciparum parasites, which have elevated cAMP and hyperactivated PKA, shows that PKA substrates (inferred to include PKAr-associated signaling) are broadly hyperphosphorylated, indicating that PKAr-mediated regulation of PKA activity is critical for correct temporal control of erythrocyte invasion and early intra-erythrocytic development.","method":"Conditional gene disruption of PDEβ; phosphoproteomic profiling; invasion and growth assays","journal":"PLoS biology","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — PKAr is identified in the phosphoproteomic dataset as part of the cAMP/PKA pathway affected, but PKAr-specific mechanistic findings are inferred from the broader PKA hyperactivation phenotype rather than directly manipulating PKAr; single lab","pmids":["30794532"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2012,"finding":"In vivo phosphoproteomic data reveal multiple phosphorylation sites in the N-terminus of the PKAr subunit; this region is predicted to be highly flexible and these phosphosites are proposed (but not experimentally confirmed in this paper) to serve as docking sites for proteins such as 14-3-3. Additionally, PKAr contains inhibitor sites that interact with the catalytic subunit to suppress PKA activity.","method":"Analysis of published phosphoproteomic datasets; bioinformatic comparison of parasite and mammalian PKA subunits","journal":"Microbes and infection","confidence":"Low","confidence_rationale":"Tier 4 / Weak — primarily bioinformatic/database analysis of existing phosphoproteomic data with no new direct experiment on PKAr reported in this paper","pmids":["22626931"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]}],"current_model":"PKAr (PF3D7_1223100) is the sole cAMP receptor regulatory subunit of P. falciparum PKA; it holds the catalytic subunit in an inactive state through allosteric inhibition, and binding of two cAMP molecules (structurally confirmed by crystal structure) releases the catalytic subunit to phosphorylate substrates such as AMA1; PKAr itself undergoes Ca2+-dependent phosphorylation in merozoites, enabling its binding to Pf14-3-3I and assembly of a multiprotein invasion-regulatory complex, while its overexpression or its activity in the cAMP pathway negatively modulates the New Permeation Pathway anion channel in infected erythrocytes."},"narrative":{"mechanistic_narrative":"PKAr (PF3D7_1223100) is the cAMP-receptor regulatory subunit of Plasmodium falciparum protein kinase A, functioning as the allosteric gatekeeper that couples cAMP signaling to erythrocyte invasion and intra-erythrocytic development [PMID:27738107, PMID:30794532]. Crystal structures of PKAr bound to cAMP and to the antimalarial analogue (Sp)-2-Cl-cAMPS establish that PKAr holds the catalytic subunit (PKA-C) inactive through allosteric inhibition, and that cooperative binding of two cAMP molecules drives a conformational change releasing PKA-C to phosphorylate downstream substrates such as AMA1 [PMID:27738107]. This sequestration role is confirmed functionally: PKAr overexpression is toxic to parasites and its growth defect is rescued by raising intracellular cAMP, consistent with PKAr titrating free catalytic subunit; the same overexpression down-regulates the New Permeation Pathway anion channel of infected erythrocytes in a cAMP-dependent manner [PMID:18248092]. Beyond its inhibitory function, PKAr is itself a signaling node: upon the high-K+ to low-K+ transition experienced by merozoites, it undergoes Ca2+-dependent phosphorylation, and the phosphorylated form is bound by Pf14-3-3I to nucleate a multiprotein complex required for microneme secretion and RBC invasion, since a phosphopeptide mimic of the PKAr phosphosite disrupts the complex and blocks invasion [PMID:32817103]. Correct temporal restraint of PKA activity by PKAr is required for ordered invasion and early development, as genetic elevation of cAMP produces broad substrate hyperphosphorylation [PMID:30794532].","teleology":[{"year":2008,"claim":"It was unknown whether the PKA regulatory subunit had any function beyond inhibiting its catalytic partner; this work showed PKAr acts through the cAMP pathway to control an ion-transport phenotype of the host erythrocyte.","evidence":"Patch-clamp electrophysiology with recombinant PKAr addition and transgenic overexpression, with cAMP rescue of the growth defect, in P. falciparum","pmids":["18248092"],"confidence":"High","gaps":["Whether PKAr directly contacts the anion channel or acts solely by sequestering catalytic subunit is not resolved","The molecular identity of the New Permeation Pathway channel is not established here"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2012,"claim":"Before direct structural or interaction data, in silico analysis proposed that N-terminal PKAr phosphosites might serve as docking sites for regulatory proteins, framing PKAr as a potential signaling hub rather than a passive inhibitor.","evidence":"Bioinformatic reanalysis of published phosphoproteomic datasets and comparison of parasite versus mammalian PKA subunits","pmids":["22626931"],"confidence":"Low","gaps":["Docking of 14-3-3 to these phosphosites was not experimentally tested in this work","No new experiment on PKAr was performed; predictions only"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2016,"claim":"It was unclear how cAMP mechanistically triggers PKA activation in the parasite; the crystal structure defined the allosteric basis, showing two cAMP molecules stabilize a conformation that releases the catalytic subunit to phosphorylate AMA1.","evidence":"X-ray crystallography of PKAr–cAMP and PKAr–(Sp)-2-Cl-cAMPS complexes with agonist-induced growth-disruption assays in P. falciparum","pmids":["27738107"],"confidence":"High","gaps":["Structure of the full PKAr–PKA-C holoenzyme was not solved","Direct in vitro phosphorylation of AMA1 by released catalytic subunit was not shown in this entry"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2019,"claim":"The physiological consequence of failing to restrain PKA was unknown; loss of cAMP degradation revealed that PKAr-mediated control of kinase activity is required for correct temporal ordering of invasion and early development.","evidence":"Conditional disruption of PDEβ producing elevated cAMP and hyperactivated PKA, with phosphoproteomic profiling and invasion/growth assays in P. falciparum","pmids":["30794532"],"confidence":"Medium","gaps":["PKAr was not directly manipulated; its specific contribution is inferred from pathway-wide hyperactivation","Individual substrates whose dysregulation drives the phenotype are not resolved for PKAr specifically"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2020,"claim":"It was unknown whether PKAr had a signaling role beyond kinase inhibition; this work showed Ca2+-dependent phosphorylation of PKAr creates a 14-3-3 docking event that assembles an invasion-regulatory complex.","evidence":"Quantitative phosphoproteomics, co-immunoprecipitation, gel filtration, phosphopeptide competition, and microneme secretion/invasion assays in P. falciparum merozoites","pmids":["32817103"],"confidence":"High","gaps":["The kinase phosphorylating PKAr in a Ca2+-dependent manner is not identified","The full composition and downstream effectors of the PKAr–Pf14-3-3I complex are not defined","How this phospho-dependent complex relates to cAMP-driven catalytic release is not integrated"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":null,"claim":"How the two regulatory modes of PKAr — cAMP-gated inhibition of the catalytic subunit and Ca2+-phosphorylation-driven 14-3-3 complex assembly — are coordinated during invasion, and which downstream substrates each controls, remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No holoenzyme structure linking the inhibitory and docking functions","The upstream Ca2+-activated kinase is unidentified","The complete substrate set downstream of released PKA-C in the parasite is undefined"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]}],"mechanism_profile":{"molecular_activity":[],"localization":[],"pathway":[],"complexes":["cAMP-dependent protein kinase (PKA) holoenzyme (PKAr with catalytic subunit PKA-C)","PKAr–Pf14-3-3I multiprotein invasion-regulatory complex"],"partners":["PKA CATALYTIC SUBUNIT (PKA-C)","PF14-3-3I","AMA1 (DOWNSTREAM SUBSTRATE OF RELEASED PKA-C)"],"other_free_text":["Binds two cAMP molecules cooperatively; also binds the antimalarial analogue (Sp)-2-Cl-cAMPS [#1]","Undergoes Ca2+-dependent phosphorylation in merozoites during the high-K+ to low-K+ transition [#2]","Overexpression negatively modulates the New Permeation Pathway anion channel of infected erythrocytes in a cAMP-dependent manner [#0]","N-terminal phosphosites proposed as 14-3-3 docking sites by bioinformatic analysis (Low confidence) [#4]"]}},"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":"18248092","id":"PMC_18248092","title":"Plasmodium falciparum regulatory subunit of cAMP-dependent PKA and anion channel conductance.","date":"2008","source":"PLoS pathogens","url":"https://pubmed.ncbi.nlm.nih.gov/18248092","citation_count":69,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["curated_ref"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"30794532","id":"PMC_30794532","title":"Phosphodiesterase beta is the master regulator of cAMP signalling during malaria parasite invasion.","date":"2019","source":"PLoS biology","url":"https://pubmed.ncbi.nlm.nih.gov/30794532","citation_count":40,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["curated_ref"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"22626931","id":"PMC_22626931","title":"Exploring the Plasmodium falciparum cyclic-adenosine monophosphate (cAMP)-dependent protein kinase (PfPKA) as a therapeutic target.","date":"2012","source":"Microbes and infection","url":"https://pubmed.ncbi.nlm.nih.gov/22626931","citation_count":35,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["curated_ref"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"27738107","id":"PMC_27738107","title":"Disrupting the Allosteric Interaction between the Plasmodium falciparum cAMP-dependent Kinase and Its Regulatory Subunit.","date":"2016","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/27738107","citation_count":13,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["PKAr"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"32817103","id":"PMC_32817103","title":"Phosphorylation-Dependent Assembly of a 14-3-3 Mediated Signaling Complex during Red Blood Cell Invasion by Plasmodium falciparum Merozoites.","date":"2020","source":"mBio","url":"https://pubmed.ncbi.nlm.nih.gov/32817103","citation_count":12,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["PKAr"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":5895,"output_tokens":1702,"usd":0.021608,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":6836,"output_tokens":3224,"usd":0.05739,"stage2_stop_reason":"end_turn"},"total_usd":0.078998,"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\": 2008,\n      \"finding\": \"Recombinant PKAr (PfPKA-R) added to the patch-clamp pipette in vitro, or overexpressed in transgenic P. falciparum parasites, down-regulates anion conductance of the infected erythrocyte membrane, demonstrating that PKAr negatively modulates the New Permeation Pathway anion channel in a cAMP-dependent manner. The growth defect caused by PKAr overexpression was restored by increasing intracellular cAMP levels, consistent with PKAr sequestering the catalytic subunit.\",\n      \"method\": \"Patch-clamp electrophysiology on infected erythrocytes with recombinant protein addition; transgenic parasite overexpression; cAMP rescue assay\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal functional assays (in vitro patch-clamp with recombinant protein plus transgenic overexpression in parasite) with pharmacological rescue, single lab but two orthogonal methods\",\n      \"pmids\": [\"18248092\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"The crystal structure of PKAr in complex with cAMP and the antimalarial analogue (Sp)-2-Cl-cAMPS was solved, revealing that PKAr holds the catalytic subunit (PKA-C) in an inactive state through allosteric inhibition, and that binding of two cAMP molecules stabilizes a conformation that releases PKA-C to phosphorylate downstream substrates such as apical membrane antigen 1 (AMA1).\",\n      \"method\": \"X-ray crystallography of PKAr–cAMP and PKAr–(Sp)-2-Cl-cAMPS complexes; functional assays with membrane-permeable cAMP agonists on parasite growth\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — crystal structure with functional validation (agonist-induced growth disruption), single lab with structural and cell-based methods\",\n      \"pmids\": [\"27738107\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"PKAr undergoes Ca2+-dependent phosphorylation in P. falciparum merozoites upon transition from high-K+ to low-K+ ionic environments. Phosphorylated PKAr is bound by Pf14-3-3I, demonstrated by co-immunoprecipitation and gel filtration chromatography, assembling a multiprotein signaling complex. A phospho-peptide mimicking PKAr Ca2+-dependent phosphosites (P1) binds Pf14-3-3I, disrupts this complex, and inhibits microneme secretion and RBC invasion.\",\n      \"method\": \"Quantitative phosphoproteomics; co-immunoprecipitation; gel filtration chromatography; phospho-peptide competition assay; microneme secretion and invasion assays\",\n      \"journal\": \"mBio\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP plus gel filtration plus phosphoproteomic identification plus functional peptide disruption assay, single lab with multiple orthogonal methods\",\n      \"pmids\": [\"32817103\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Phosphoproteomic analysis of PDEβ-null P. falciparum parasites, which have elevated cAMP and hyperactivated PKA, shows that PKA substrates (inferred to include PKAr-associated signaling) are broadly hyperphosphorylated, indicating that PKAr-mediated regulation of PKA activity is critical for correct temporal control of erythrocyte invasion and early intra-erythrocytic development.\",\n      \"method\": \"Conditional gene disruption of PDEβ; phosphoproteomic profiling; invasion and growth assays\",\n      \"journal\": \"PLoS biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — PKAr is identified in the phosphoproteomic dataset as part of the cAMP/PKA pathway affected, but PKAr-specific mechanistic findings are inferred from the broader PKA hyperactivation phenotype rather than directly manipulating PKAr; single lab\",\n      \"pmids\": [\"30794532\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"In vivo phosphoproteomic data reveal multiple phosphorylation sites in the N-terminus of the PKAr subunit; this region is predicted to be highly flexible and these phosphosites are proposed (but not experimentally confirmed in this paper) to serve as docking sites for proteins such as 14-3-3. Additionally, PKAr contains inhibitor sites that interact with the catalytic subunit to suppress PKA activity.\",\n      \"method\": \"Analysis of published phosphoproteomic datasets; bioinformatic comparison of parasite and mammalian PKA subunits\",\n      \"journal\": \"Microbes and infection\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 4 / Weak — primarily bioinformatic/database analysis of existing phosphoproteomic data with no new direct experiment on PKAr reported in this paper\",\n      \"pmids\": [\"22626931\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    }\n  ],\n  \"current_model\": \"PKAr (PF3D7_1223100) is the sole cAMP receptor regulatory subunit of P. falciparum PKA; it holds the catalytic subunit in an inactive state through allosteric inhibition, and binding of two cAMP molecules (structurally confirmed by crystal structure) releases the catalytic subunit to phosphorylate substrates such as AMA1; PKAr itself undergoes Ca2+-dependent phosphorylation in merozoites, enabling its binding to Pf14-3-3I and assembly of a multiprotein invasion-regulatory complex, while its overexpression or its activity in the cAMP pathway negatively modulates the New Permeation Pathway anion channel in infected erythrocytes.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"PKAr (PF3D7_1223100) is the cAMP-receptor regulatory subunit of Plasmodium falciparum protein kinase A, functioning as the allosteric gatekeeper that couples cAMP signaling to erythrocyte invasion and intra-erythrocytic development [#1, #3]. Crystal structures of PKAr bound to cAMP and to the antimalarial analogue (Sp)-2-Cl-cAMPS establish that PKAr holds the catalytic subunit (PKA-C) inactive through allosteric inhibition, and that cooperative binding of two cAMP molecules drives a conformational change releasing PKA-C to phosphorylate downstream substrates such as AMA1 [#1]. This sequestration role is confirmed functionally: PKAr overexpression is toxic to parasites and its growth defect is rescued by raising intracellular cAMP, consistent with PKAr titrating free catalytic subunit; the same overexpression down-regulates the New Permeation Pathway anion channel of infected erythrocytes in a cAMP-dependent manner [#0]. Beyond its inhibitory function, PKAr is itself a signaling node: upon the high-K+ to low-K+ transition experienced by merozoites, it undergoes Ca2+-dependent phosphorylation, and the phosphorylated form is bound by Pf14-3-3I to nucleate a multiprotein complex required for microneme secretion and RBC invasion, since a phosphopeptide mimic of the PKAr phosphosite disrupts the complex and blocks invasion [#2]. Correct temporal restraint of PKA activity by PKAr is required for ordered invasion and early development, as genetic elevation of cAMP produces broad substrate hyperphosphorylation [#3].\",\n  \"teleology\": [\n    {\n      \"year\": 2008,\n      \"claim\": \"It was unknown whether the PKA regulatory subunit had any function beyond inhibiting its catalytic partner; this work showed PKAr acts through the cAMP pathway to control an ion-transport phenotype of the host erythrocyte.\",\n      \"evidence\": \"Patch-clamp electrophysiology with recombinant PKAr addition and transgenic overexpression, with cAMP rescue of the growth defect, in P. falciparum\",\n      \"pmids\": [\n        \"18248092\"\n      ],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Whether PKAr directly contacts the anion channel or acts solely by sequestering catalytic subunit is not resolved\",\n        \"The molecular identity of the New Permeation Pathway channel is not established here\"\n      ],\n      \"attribution\": [\n        {\n          \"species\": \"Plasmodium falciparum\",\n          \"strain\": \"\"\n        }\n      ]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Before direct structural or interaction data, in silico analysis proposed that N-terminal PKAr phosphosites might serve as docking sites for regulatory proteins, framing PKAr as a potential signaling hub rather than a passive inhibitor.\",\n      \"evidence\": \"Bioinformatic reanalysis of published phosphoproteomic datasets and comparison of parasite versus mammalian PKA subunits\",\n      \"pmids\": [\n        \"22626931\"\n      ],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"Docking of 14-3-3 to these phosphosites was not experimentally tested in this work\",\n        \"No new experiment on PKAr was performed; predictions only\"\n      ],\n      \"attribution\": [\n        {\n          \"species\": \"Plasmodium falciparum\",\n          \"strain\": \"\"\n        }\n      ]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"It was unclear how cAMP mechanistically triggers PKA activation in the parasite; the crystal structure defined the allosteric basis, showing two cAMP molecules stabilize a conformation that releases the catalytic subunit to phosphorylate AMA1.\",\n      \"evidence\": \"X-ray crystallography of PKAr–cAMP and PKAr–(Sp)-2-Cl-cAMPS complexes with agonist-induced growth-disruption assays in P. falciparum\",\n      \"pmids\": [\n        \"27738107\"\n      ],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Structure of the full PKAr–PKA-C holoenzyme was not solved\",\n        \"Direct in vitro phosphorylation of AMA1 by released catalytic subunit was not shown in this entry\"\n      ],\n      \"attribution\": [\n        {\n          \"species\": \"Plasmodium falciparum\",\n          \"strain\": \"\"\n        }\n      ]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"The physiological consequence of failing to restrain PKA was unknown; loss of cAMP degradation revealed that PKAr-mediated control of kinase activity is required for correct temporal ordering of invasion and early development.\",\n      \"evidence\": \"Conditional disruption of PDEβ producing elevated cAMP and hyperactivated PKA, with phosphoproteomic profiling and invasion/growth assays in P. falciparum\",\n      \"pmids\": [\n        \"30794532\"\n      ],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"PKAr was not directly manipulated; its specific contribution is inferred from pathway-wide hyperactivation\",\n        \"Individual substrates whose dysregulation drives the phenotype are not resolved for PKAr specifically\"\n      ],\n      \"attribution\": [\n        {\n          \"species\": \"Plasmodium falciparum\",\n          \"strain\": \"\"\n        }\n      ]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"It was unknown whether PKAr had a signaling role beyond kinase inhibition; this work showed Ca2+-dependent phosphorylation of PKAr creates a 14-3-3 docking event that assembles an invasion-regulatory complex.\",\n      \"evidence\": \"Quantitative phosphoproteomics, co-immunoprecipitation, gel filtration, phosphopeptide competition, and microneme secretion/invasion assays in P. falciparum merozoites\",\n      \"pmids\": [\n        \"32817103\"\n      ],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"The kinase phosphorylating PKAr in a Ca2+-dependent manner is not identified\",\n        \"The full composition and downstream effectors of the PKAr–Pf14-3-3I complex are not defined\",\n        \"How this phospho-dependent complex relates to cAMP-driven catalytic release is not integrated\"\n      ],\n      \"attribution\": [\n        {\n          \"species\": \"Plasmodium falciparum\",\n          \"strain\": \"\"\n        }\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How the two regulatory modes of PKAr — cAMP-gated inhibition of the catalytic subunit and Ca2+-phosphorylation-driven 14-3-3 complex assembly — are coordinated during invasion, and which downstream substrates each controls, remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"No holoenzyme structure linking the inhibitory and docking functions\",\n        \"The upstream Ca2+-activated kinase is unidentified\",\n        \"The complete substrate set downstream of released PKA-C in the parasite is undefined\"\n      ],\n      \"attribution\": [\n        {\n          \"species\": \"Plasmodium falciparum\",\n          \"strain\": \"\"\n        }\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\n        \"term_id\": \"GO:0030552\",\n        \"supporting_discovery_ids\": [\n          1\n        ]\n      },\n      {\n        \"term_id\": \"GO:0008603\",\n        \"supporting_discovery_ids\": [\n          0,\n          1,\n          3\n        ]\n      },\n      {\n        \"term_id\": \"GO:0004862\",\n        \"supporting_discovery_ids\": [\n          1,\n          4\n        ]\n      }\n    ],\n    \"localization\": [],\n    \"pathway\": [\n      {\n        \"term_id\": \"GO:0034199\",\n        \"supporting_discovery_ids\": [\n          0,\n          1,\n          3\n        ]\n      },\n      {\n        \"term_id\": \"GO:0044409\",\n        \"supporting_discovery_ids\": [\n          2\n        ]\n      }\n    ],\n    \"complexes\": [\n      \"cAMP-dependent protein kinase (PKA) holoenzyme (PKAr with catalytic subunit PKA-C)\",\n      \"PKAr–Pf14-3-3I multiprotein invasion-regulatory complex\"\n    ],\n    \"partners\": [\n      \"PKA catalytic subunit (PKA-C)\",\n      \"Pf14-3-3I\",\n      \"AMA1 (downstream substrate of released PKA-C)\"\n    ],\n    \"other_free_text\": [\n      \"Binds two cAMP molecules cooperatively; also binds the antimalarial analogue (Sp)-2-Cl-cAMPS [#1]\",\n      \"Undergoes Ca2+-dependent phosphorylation in merozoites during the high-K+ to low-K+ transition [#2]\",\n      \"Overexpression negatively modulates the New Permeation Pathway anion channel of infected erythrocytes in a cAMP-dependent manner [#0]\",\n      \"N-terminal phosphosites proposed as 14-3-3 docking sites by bioinformatic analysis (Low confidence) [#4]\"\n    ]\n  }\n}","audit_flag":{"gene":"PF3D7_1223100","tier":"IDENTITY_CHECK","verdict":"identity unverified","subtype":"names_other_cards","uniprot_band":"","rules_fired":"R12","issue":"No cited paper names this card; 5 of 5 cited papers name other catalogue genes (PF3D7_0934800, PF3D7_0217500, PF3D7_0818200). The summary may describe one of those genes."},"strains":[{"strain":"Pf3D7","gene_id":"PF3D7_1223100","name":null,"product":"cAMP-dependent protein kinase regulatory subunit","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PbANKA","gene_id":"PBANKA_1438000","name":null,"product":"cAMP-dependent protein kinase regulatory subunit, putative","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PkH","gene_id":"PKNH_1442300","name":null,"product":"cAMP-dependent protein kinase regulatory subunit, putative","uniprot_acc":null,"chromosome":null,"start_pos":null}],"gene_symbol":"PKAr","evaluation":null}