{"gene":"PF3D7_1446600","run_date":"2026-09-08T14:19:07","timeline":{"discoveries":[{"year":2008,"finding":"P. falciparum CEN2 (one of four PfCENs characterized) is expressed in sporozoites, asexual blood forms, gametocytes, and oocysts; immunoelectron microscopy showed centrin localizes in close proximity to the nucleus of sporozoites and asexual schizonts, and double-staining with alpha-tubulin antibodies indicated association with the parasite centrosome. Episomal expression of CEN2 (among the four PfCENs) in a centrin-knockout Leishmania donovani line partially restored growth rate and rescued the cytokinesis defect, providing functional evidence for a role in cell division.","method":"Immunoelectron microscopy, confocal/widefield immunofluorescence with alpha-tubulin co-staining, real-time PCR, growth complementation in centrin-knockout Leishmania donovani","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — functional complementation assay and localization data from a single lab; the complementation result is attributed to one of four PfCENs without specifying which one restored growth, limiting attribution precision to CEN2 specifically","pmids":["18693242"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2020,"finding":"In P. berghei, centrin-2 co-localizes with kinesin-5-GFP and alpha-tubulin at spindle poles during blood stage schizogony, as shown by fixed-cell immunofluorescence, establishing centrin-2 as a spindle pole marker during mitosis in this species.","method":"Fixed-cell immunofluorescence co-localization with alpha-tubulin and kinesin-5-GFP during blood stage schizogony","journal":"Frontiers in cellular and infection microbiology","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single co-localization experiment in one lab; centrin-2 used as a reference marker, no direct functional manipulation of centrin-2 itself","pmids":["33154955"],"is_preprint":false,"attribution":[{"species":"Plasmodium berghei","strain":""}]},{"year":2024,"finding":"P. falciparum CEN2 (EF-hand containing Centrin 2, PF3D7_1446600) partially localizes to the posterior cup subcompartment of the basal complex during schizogony, as demonstrated by ultrastructure expansion microscopy. CEN2 is essential for parasite growth and replication, with conditional loss-of-function producing variable defects in basal complex contraction and synchrony. Free intracellular calcium is necessary but not sufficient for basal complex contraction, implicating CEN2's EF-hand calcium-binding function in this process.","method":"Ultrastructure expansion microscopy (localization), live-cell microscopy, conditional loss-of-function with phenotypic readout (basal complex contraction defects, growth/replication arrest)","journal":"PLoS pathogens","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct localization by expansion microscopy and conditional loss-of-function with specific cellular phenotype (basal complex contraction defects), single lab but two orthogonal methods","pmids":["38829893"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]}],"current_model":"P. falciparum CEN2 (PF3D7_1446600) is an EF-hand calcium-binding cytoskeletal protein that associates with the centrosome/spindle poles during schizogony and partially localizes to the posterior cup subcompartment of the basal complex during cytokinesis, where it is essential for parasite growth and normal basal complex contraction, with free intracellular calcium necessary but not sufficient for this contractile process."},"narrative":{"mechanistic_narrative":"CEN2 (PF3D7_1446600) is an EF-hand calcium-binding centrin that functions in Plasmodium cell division, associating with the centrosome and spindle-pole apparatus during schizogony [PMID:18693242]. In P. falciparum, immunoelectron microscopy places centrin in close proximity to the nucleus of sporozoites and asexual schizonts in association with the parasite centrosome, and episomal expression of CEN2 partially rescues growth and the cytokinesis defect of a centrin-knockout Leishmania donovani line, giving functional support for a role in cell division [PMID:18693242]. During cytokinesis, CEN2 partially localizes to the posterior cup subcompartment of the basal complex; conditional loss of function arrests parasite growth and replication and produces variable defects in basal complex contraction and synchrony, and free intracellular calcium is necessary but not sufficient for this contraction, implicating the EF-hand calcium-binding activity of CEN2 in the process [PMID:38829893]. Beyond its centrosome/spindle-pole and basal-complex association and this contractile role, no further mechanistic detail—including direct binding partners or the calcium-transduction mechanism—has been characterized for CEN2 in the available corpus.","teleology":[{"year":2008,"claim":"Whether Plasmodium centrin proteins act in cell division was unresolved; localizing CEN2 to the centrosome and testing it in a functional complementation assay established a division-associated role.","evidence":"Immunoelectron microscopy and alpha-tubulin co-staining in P. falciparum sporozoites/schizonts plus growth and cytokinesis complementation in centrin-knockout Leishmania donovani","pmids":["18693242"],"confidence":"Medium","gaps":["The complementation result was attributed to one of four PfCENs without specifying CEN2 as the rescuing member, limiting attribution precision","No direct calcium-binding or biochemical activity demonstrated for CEN2 itself","No binding partners at the centrosome identified"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2020,"claim":"It was unclear where centrin-2 sits relative to the mitotic spindle during schizogony; co-localization with spindle-pole markers positioned it as a spindle-pole marker in blood-stage mitosis.","evidence":"Fixed-cell immunofluorescence co-localization with alpha-tubulin and kinesin-5-GFP during P. berghei blood-stage schizogony","pmids":["33154955"],"confidence":"Low","gaps":["Single co-localization experiment with centrin-2 used only as a reference marker, no functional manipulation of centrin-2","Shown in P. berghei, not P. falciparum","Does not establish whether spindle-pole localization is required for mitotic function"],"attribution":[{"species":"Plasmodium berghei","strain":""}]},{"year":2024,"claim":"Whether CEN2 contributes to cytokinesis at a specific structure was unknown; expansion microscopy and conditional knockdown placed it at the basal complex posterior cup and showed it is essential for contraction and replication.","evidence":"Ultrastructure expansion microscopy, live-cell imaging, and conditional loss-of-function with basal-complex contraction and growth phenotypes in P. falciparum","pmids":["38829893"],"confidence":"Medium","gaps":["Loss-of-function produced variable rather than fully penetrant contraction defects, leaving the precise requirement unclear","How calcium binding by CEN2 is transduced into basal complex contraction is not defined","Direct molecular partners at the posterior cup remain unidentified"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":null,"claim":"The direct binding partners and the biochemical mechanism by which CEN2 calcium binding drives basal complex contraction and spindle-pole function remain unknown.","evidence":"","pmids":[],"confidence":"Low","gaps":["No reconstitution or direct calcium-binding assay for CEN2 in the corpus","No identified interaction partners at the centrosome or posterior cup","Mechanism linking calcium flux to contraction not established"],"attribution":[]}],"mechanism_profile":{"molecular_activity":[],"localization":[],"pathway":[],"complexes":["basal complex (posterior cup subcompartment)"],"partners":[],"other_free_text":["Associates with the centrosome/spindle poles during schizogony; co-localizes with alpha-tubulin and, in P. berghei, kinesin-5-GFP at spindle poles [#0, #1]","Conditional loss-of-function arrests P. falciparum growth/replication and impairs basal complex contraction and synchrony [#2]","Free intracellular calcium is necessary but not sufficient for basal complex contraction, implicating CEN2 EF-hand function [#2]","Episomal CEN2 expression partially rescues growth and cytokinesis in a centrin-knockout Leishmania donovani line [#0]"]}},"prefetch_data":{},"corpus_meta":[{"pmid":"18693242","id":"PMC_18693242","title":"Centrins, cell cycle regulation proteins in human malaria parasite Plasmodium falciparum.","date":"2008","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/18693242","citation_count":68,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["curated_ref"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"33154955","id":"PMC_33154955","title":"Plasmodium berghei Kinesin-5 Associates With the Spindle Apparatus During Cell Division and Is Important for Efficient Production of Infectious Sporozoites.","date":"2020","source":"Frontiers in cellular and infection microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/33154955","citation_count":18,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["centrin-2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"38829893","id":"PMC_38829893","title":"Elucidating the spatio-temporal dynamics of the Plasmodium falciparum basal complex.","date":"2024","source":"PLoS pathogens","url":"https://pubmed.ncbi.nlm.nih.gov/38829893","citation_count":4,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["centrin-2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":4533,"output_tokens":1100,"usd":0.01505,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":5860,"output_tokens":2121,"usd":0.041162,"stage2_stop_reason":"end_turn"},"total_usd":0.056212,"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\": \"P. falciparum CEN2 (one of four PfCENs characterized) is expressed in sporozoites, asexual blood forms, gametocytes, and oocysts; immunoelectron microscopy showed centrin localizes in close proximity to the nucleus of sporozoites and asexual schizonts, and double-staining with alpha-tubulin antibodies indicated association with the parasite centrosome. Episomal expression of CEN2 (among the four PfCENs) in a centrin-knockout Leishmania donovani line partially restored growth rate and rescued the cytokinesis defect, providing functional evidence for a role in cell division.\",\n      \"method\": \"Immunoelectron microscopy, confocal/widefield immunofluorescence with alpha-tubulin co-staining, real-time PCR, growth complementation in centrin-knockout Leishmania donovani\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — functional complementation assay and localization data from a single lab; the complementation result is attributed to one of four PfCENs without specifying which one restored growth, limiting attribution precision to CEN2 specifically\",\n      \"pmids\": [\"18693242\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}\n      ]\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"In P. berghei, centrin-2 co-localizes with kinesin-5-GFP and alpha-tubulin at spindle poles during blood stage schizogony, as shown by fixed-cell immunofluorescence, establishing centrin-2 as a spindle pole marker during mitosis in this species.\",\n      \"method\": \"Fixed-cell immunofluorescence co-localization with alpha-tubulin and kinesin-5-GFP during blood stage schizogony\",\n      \"journal\": \"Frontiers in cellular and infection microbiology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single co-localization experiment in one lab; centrin-2 used as a reference marker, no direct functional manipulation of centrin-2 itself\",\n      \"pmids\": [\"33154955\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Plasmodium berghei\", \"strain\": \"\"}\n      ]\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"P. falciparum CEN2 (EF-hand containing Centrin 2, PF3D7_1446600) partially localizes to the posterior cup subcompartment of the basal complex during schizogony, as demonstrated by ultrastructure expansion microscopy. CEN2 is essential for parasite growth and replication, with conditional loss-of-function producing variable defects in basal complex contraction and synchrony. Free intracellular calcium is necessary but not sufficient for basal complex contraction, implicating CEN2's EF-hand calcium-binding function in this process.\",\n      \"method\": \"Ultrastructure expansion microscopy (localization), live-cell microscopy, conditional loss-of-function with phenotypic readout (basal complex contraction defects, growth/replication arrest)\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct localization by expansion microscopy and conditional loss-of-function with specific cellular phenotype (basal complex contraction defects), single lab but two orthogonal methods\",\n      \"pmids\": [\"38829893\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}\n      ]\n    }\n  ],\n  \"current_model\": \"P. falciparum CEN2 (PF3D7_1446600) is an EF-hand calcium-binding cytoskeletal protein that associates with the centrosome/spindle poles during schizogony and partially localizes to the posterior cup subcompartment of the basal complex during cytokinesis, where it is essential for parasite growth and normal basal complex contraction, with free intracellular calcium necessary but not sufficient for this contractile process.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"CEN2 (PF3D7_1446600) is an EF-hand calcium-binding centrin that functions in Plasmodium cell division, associating with the centrosome and spindle-pole apparatus during schizogony [#0]. In P. falciparum, immunoelectron microscopy places centrin in close proximity to the nucleus of sporozoites and asexual schizonts in association with the parasite centrosome, and episomal expression of CEN2 partially rescues growth and the cytokinesis defect of a centrin-knockout Leishmania donovani line, giving functional support for a role in cell division [#0]. During cytokinesis, CEN2 partially localizes to the posterior cup subcompartment of the basal complex; conditional loss of function arrests parasite growth and replication and produces variable defects in basal complex contraction and synchrony, and free intracellular calcium is necessary but not sufficient for this contraction, implicating the EF-hand calcium-binding activity of CEN2 in the process [#2]. Beyond its centrosome/spindle-pole and basal-complex association and this contractile role, no further mechanistic detail—including direct binding partners or the calcium-transduction mechanism—has been characterized for CEN2 in the available corpus.\",\n  \"teleology\": [\n    {\n      \"year\": 2008,\n      \"claim\": \"Whether Plasmodium centrin proteins act in cell division was unresolved; localizing CEN2 to the centrosome and testing it in a functional complementation assay established a division-associated role.\",\n      \"evidence\": \"Immunoelectron microscopy and alpha-tubulin co-staining in P. falciparum sporozoites/schizonts plus growth and cytokinesis complementation in centrin-knockout Leishmania donovani\",\n      \"pmids\": [\"18693242\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"The complementation result was attributed to one of four PfCENs without specifying CEN2 as the rescuing member, limiting attribution precision\",\n        \"No direct calcium-binding or biochemical activity demonstrated for CEN2 itself\",\n        \"No binding partners at the centrosome identified\"\n      ],\n      \"attribution\": [\n        {\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}\n      ]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"It was unclear where centrin-2 sits relative to the mitotic spindle during schizogony; co-localization with spindle-pole markers positioned it as a spindle-pole marker in blood-stage mitosis.\",\n      \"evidence\": \"Fixed-cell immunofluorescence co-localization with alpha-tubulin and kinesin-5-GFP during P. berghei blood-stage schizogony\",\n      \"pmids\": [\"33154955\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"Single co-localization experiment with centrin-2 used only as a reference marker, no functional manipulation of centrin-2\",\n        \"Shown in P. berghei, not P. falciparum\",\n        \"Does not establish whether spindle-pole localization is required for mitotic function\"\n      ],\n      \"attribution\": [\n        {\"species\": \"Plasmodium berghei\", \"strain\": \"\"}\n      ]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Whether CEN2 contributes to cytokinesis at a specific structure was unknown; expansion microscopy and conditional knockdown placed it at the basal complex posterior cup and showed it is essential for contraction and replication.\",\n      \"evidence\": \"Ultrastructure expansion microscopy, live-cell imaging, and conditional loss-of-function with basal-complex contraction and growth phenotypes in P. falciparum\",\n      \"pmids\": [\"38829893\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Loss-of-function produced variable rather than fully penetrant contraction defects, leaving the precise requirement unclear\",\n        \"How calcium binding by CEN2 is transduced into basal complex contraction is not defined\",\n        \"Direct molecular partners at the posterior cup remain unidentified\"\n      ],\n      \"attribution\": [\n        {\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The direct binding partners and the biochemical mechanism by which CEN2 calcium binding drives basal complex contraction and spindle-pole function remain unknown.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"No reconstitution or direct calcium-binding assay for CEN2 in the corpus\",\n        \"No identified interaction partners at the centrosome or posterior cup\",\n        \"Mechanism linking calcium flux to contraction not established\"\n      ],\n      \"attribution\": []\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0005509\", \"supporting_discovery_ids\": [2]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005813\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"GO:0000922\", \"supporting_discovery_ids\": [1]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0000910\", \"supporting_discovery_ids\": [0, 2]},\n      {\"term_id\": \"GO:0051301\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"complexes\": [\n      \"basal complex (posterior cup subcompartment)\"\n    ],\n    \"partners\": [],\n    \"other_free_text\": [\n      \"Associates with the centrosome/spindle poles during schizogony; co-localizes with alpha-tubulin and, in P. berghei, kinesin-5-GFP at spindle poles [#0, #1]\",\n      \"Conditional loss-of-function arrests P. falciparum growth/replication and impairs basal complex contraction and synchrony [#2]\",\n      \"Free intracellular calcium is necessary but not sufficient for basal complex contraction, implicating CEN2 EF-hand function [#2]\",\n      \"Episomal CEN2 expression partially rescues growth and cytokinesis in a centrin-knockout Leishmania donovani line [#0]\"\n    ]\n  }\n}","audit_flag":{"gene":"PF3D7_1446600","tier":"IDENTITY_CHECK","verdict":"identity unverified","subtype":"names_other_cards","uniprot_band":"","rules_fired":"R12","issue":"No cited paper names this card; 2 of 3 cited papers name other catalogue genes (PF3D7_0111000, PF3D7_0616200, PF3D7_0214700). The summary may describe one of those genes."},"strains":[{"strain":"Pf3D7","gene_id":"PF3D7_1446600","name":null,"product":"centrin-2","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PbANKA","gene_id":"PBANKA_1310400","name":null,"product":"centrin-2, putative","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PkH","gene_id":"PKNH_1235600","name":null,"product":"centrin-2, putative","uniprot_acc":null,"chromosome":null,"start_pos":null}],"gene_symbol":"CEN2","evaluation":null}