{"gene":"PF3D7_0818100","run_date":"2026-09-08T12:51:27","timeline":{"discoveries":[{"year":2022,"finding":"CZIF2 (PF3D7_0818100) localizes to discrete foci on the periphery of the parasite cytosol and is peripherally associated with a membrane, as determined by immunofluorescence localization and biochemical assays in P. falciparum asexual (late schizogony) stages.","method":"Immunofluorescence localization and biochemical membrane-association assays","journal":"International journal for parasitology","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — immunofluorescence and biochemical fractionation in a single study, two orthogonal methods establishing localization","pmids":["36400305"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2022,"finding":"Gene knockout of CZIF2 (PF3D7_0818100) alone does not abolish blood stage growth; however, simultaneous knockout of both Pfczif1 and Pfczif2 could not be achieved, indicating that at least one of the two genes is essential for in vitro parasite growth.","method":"Gene knockout (CRISPR/genetic disruption) with growth assays and attempted double knockout","journal":"International journal for parasitology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean KO with defined cellular phenotype and epistatic double-KO test, single lab","pmids":["36400305"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2022,"finding":"C-terminal truncation of CZIF2 (PF3D7_0818100) alters the expression of some exported proteins, including PfKAHRP, as revealed by transcriptomic analysis of the truncation mutant, suggesting CZIF2 may help regulate expression of proteins exported into the red blood cell cytosol after merozoite invasion.","method":"C-terminal truncation mutagenesis combined with transcriptomic (RNA-seq) analysis","journal":"International journal for parasitology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic truncation mutant with transcriptomic readout, single lab, two orthogonal approaches within one study","pmids":["36400305"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2022,"finding":"CZIF2 (PF3D7_0818100) has peak expression during late schizogony of blood stages, identifying it as one of only two C3H1-type zinc finger proteins in P. falciparum with this temporal expression pattern.","method":"Transcriptomic analysis of stage-specific expression","journal":"International journal for parasitology","confidence":"Low","confidence_rationale":"Tier 4 / Weak — expression-based identification; included only because it defines the biological context for mechanistic follow-up but the underlying evidence is transcriptomic","pmids":["36400305"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]}],"current_model":"CZIF2 (PF3D7_0818100) is a C3H1-type zinc finger protein that is expressed during late schizogony in P. falciparum blood stages, localizes to discrete foci on the periphery of the parasite cytosol where it is peripherally associated with a membrane, is individually dispensable for blood-stage growth but functionally redundant with PfCZIF1 (at least one must be present), and appears to regulate the expression of exported proteins—including PfKAHRP—rather than playing a direct role in merozoite invasion of red blood cells."},"narrative":{"mechanistic_narrative":"CZIF2 (PF3D7_0818100) is a C3H1-type zinc finger protein of P. falciparum that participates in the regulation of protein export during asexual blood-stage development [PMID:36400305]. During late schizogony it localizes to discrete foci at the periphery of the parasite cytosol, where it is peripherally associated with a membrane [PMID:36400305]. CZIF2 is individually dispensable for blood-stage growth, but it is functionally redundant with PfCZIF1: while single knockout of CZIF2 is tolerated, a double knockout of both genes cannot be obtained, indicating that at least one of the pair is essential for in vitro growth [PMID:36400305]. C-terminal truncation of CZIF2 alters the expression of exported proteins, including PfKAHRP, positioning it as a regulator of proteins destined for the red blood cell cytosol rather than a direct effector of merozoite invasion [PMID:36400305]. Beyond these findings, no substrates, RNA targets, or direct interaction partners of CZIF2 have been characterized in the available corpus.","teleology":[{"year":2022,"claim":"Establishing where and when CZIF2 acts was the first step in placing it in the blood-stage program; localization to peripheral cytosolic foci associated with a membrane during late schizogony framed it as a stage-specific factor rather than a housekeeping protein.","evidence":"Immunofluorescence localization and biochemical membrane-association assays, plus stage-specific transcriptomic profiling in P. falciparum asexual stages","pmids":["36400305"],"confidence":"Medium","gaps":["The identity of the membrane compartment CZIF2 associates with is not defined","The functional meaning of the discrete peripheral foci is unknown","No direct partner mediating membrane association identified"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2022,"claim":"Whether CZIF2 is essential was resolved genetically: single knockout is tolerated but the double knockout with Pfczif1 cannot be achieved, establishing functional redundancy in which at least one of the two paralogs is required for growth.","evidence":"Gene knockout with growth assays and an attempted double knockout in P. falciparum","pmids":["36400305"],"confidence":"Medium","gaps":["The shared molecular activity that makes the pair collectively essential is unknown","Whether CZIF1 and CZIF2 act on the same targets is not directly demonstrated","Failure to obtain the double knockout is inferred essentiality, not a conditional-depletion phenotype"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2022,"claim":"Assigning a downstream role, C-terminal truncation altered expression of exported proteins including PfKAHRP, linking CZIF2 to regulation of the export program rather than to invasion.","evidence":"C-terminal truncation mutagenesis combined with RNA-seq transcriptomic analysis in P. falciparum","pmids":["36400305"],"confidence":"Medium","gaps":["Whether CZIF2 regulates exported-protein genes directly or indirectly is not established","No RNA or protein target of the zinc finger domain has been identified","The mechanism by which the C-terminus contributes to this regulation is unresolved"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":null,"claim":"The molecular mechanism by which CZIF2 regulates exported protein expression, and whether it acts as an RNA-binding regulator via its C3H1 zinc finger, remains unresolved.","evidence":"","pmids":[],"confidence":"Low","gaps":["No direct RNA or protein targets identified","No biochemical demonstration of nucleic-acid binding by CZIF2","Relationship between CZIF2 and PfCZIF1 at the molecular level uncharacterized"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]}],"mechanism_profile":{"molecular_activity":[],"localization":[],"pathway":[],"complexes":[],"partners":["PFCZIF1 (FUNCTIONAL REDUNDANCY; NOT A DEMONSTRATED PHYSICAL INTERACTION)"],"other_free_text":["C3H1-type zinc finger protein with peak expression during late schizogony of blood stages [#3].","Individually dispensable for blood-stage growth; essential only in combination with PfCZIF1 [#1].","C-terminal truncation alters expression of exported proteins including PfKAHRP [#2]."]}},"prefetch_data":{},"corpus_meta":[{"pmid":"36400305","id":"PMC_36400305","title":"Characterisation of PfCZIF1 and PfCZIF2 in Plasmodium falciparum asexual stages.","date":"2022","source":"International journal for parasitology","url":"https://pubmed.ncbi.nlm.nih.gov/36400305","citation_count":5,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["C3H1","PfCZIF2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":3477,"output_tokens":1071,"usd":0.013248,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":5872,"output_tokens":1831,"usd":0.037567,"stage2_stop_reason":"end_turn"},"total_usd":0.050815,"stage1_batch_id":"msgbatch_01DisAaTypwmC8QwdMBuePHo","stage2_batch_id":"msgbatch_0184zxZTqxiEfdYYfPMfkqjb","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2022,\n      \"finding\": \"CZIF2 (PF3D7_0818100) localizes to discrete foci on the periphery of the parasite cytosol and is peripherally associated with a membrane, as determined by immunofluorescence localization and biochemical assays in P. falciparum asexual (late schizogony) stages.\",\n      \"method\": \"Immunofluorescence localization and biochemical membrane-association assays\",\n      \"journal\": \"International journal for parasitology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — immunofluorescence and biochemical fractionation in a single study, two orthogonal methods establishing localization\",\n      \"pmids\": [\"36400305\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Gene knockout of CZIF2 (PF3D7_0818100) alone does not abolish blood stage growth; however, simultaneous knockout of both Pfczif1 and Pfczif2 could not be achieved, indicating that at least one of the two genes is essential for in vitro parasite growth.\",\n      \"method\": \"Gene knockout (CRISPR/genetic disruption) with growth assays and attempted double knockout\",\n      \"journal\": \"International journal for parasitology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean KO with defined cellular phenotype and epistatic double-KO test, single lab\",\n      \"pmids\": [\"36400305\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"C-terminal truncation of CZIF2 (PF3D7_0818100) alters the expression of some exported proteins, including PfKAHRP, as revealed by transcriptomic analysis of the truncation mutant, suggesting CZIF2 may help regulate expression of proteins exported into the red blood cell cytosol after merozoite invasion.\",\n      \"method\": \"C-terminal truncation mutagenesis combined with transcriptomic (RNA-seq) analysis\",\n      \"journal\": \"International journal for parasitology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic truncation mutant with transcriptomic readout, single lab, two orthogonal approaches within one study\",\n      \"pmids\": [\"36400305\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"CZIF2 (PF3D7_0818100) has peak expression during late schizogony of blood stages, identifying it as one of only two C3H1-type zinc finger proteins in P. falciparum with this temporal expression pattern.\",\n      \"method\": \"Transcriptomic analysis of stage-specific expression\",\n      \"journal\": \"International journal for parasitology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 4 / Weak — expression-based identification; included only because it defines the biological context for mechanistic follow-up but the underlying evidence is transcriptomic\",\n      \"pmids\": [\"36400305\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    }\n  ],\n  \"current_model\": \"CZIF2 (PF3D7_0818100) is a C3H1-type zinc finger protein that is expressed during late schizogony in P. falciparum blood stages, localizes to discrete foci on the periphery of the parasite cytosol where it is peripherally associated with a membrane, is individually dispensable for blood-stage growth but functionally redundant with PfCZIF1 (at least one must be present), and appears to regulate the expression of exported proteins—including PfKAHRP—rather than playing a direct role in merozoite invasion of red blood cells.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"CZIF2 (PF3D7_0818100) is a C3H1-type zinc finger protein of P. falciparum that participates in the regulation of protein export during asexual blood-stage development [#0, #2]. During late schizogony it localizes to discrete foci at the periphery of the parasite cytosol, where it is peripherally associated with a membrane [#0]. CZIF2 is individually dispensable for blood-stage growth, but it is functionally redundant with PfCZIF1: while single knockout of CZIF2 is tolerated, a double knockout of both genes cannot be obtained, indicating that at least one of the pair is essential for in vitro growth [#1]. C-terminal truncation of CZIF2 alters the expression of exported proteins, including PfKAHRP, positioning it as a regulator of proteins destined for the red blood cell cytosol rather than a direct effector of merozoite invasion [#2]. Beyond these findings, no substrates, RNA targets, or direct interaction partners of CZIF2 have been characterized in the available corpus.\",\n  \"teleology\": [\n    {\n      \"year\": 2022,\n      \"claim\": \"Establishing where and when CZIF2 acts was the first step in placing it in the blood-stage program; localization to peripheral cytosolic foci associated with a membrane during late schizogony framed it as a stage-specific factor rather than a housekeeping protein.\",\n      \"evidence\": \"Immunofluorescence localization and biochemical membrane-association assays, plus stage-specific transcriptomic profiling in P. falciparum asexual stages\",\n      \"pmids\": [\"36400305\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"The identity of the membrane compartment CZIF2 associates with is not defined\",\n        \"The functional meaning of the discrete peripheral foci is unknown\",\n        \"No direct partner mediating membrane association identified\"\n      ],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Whether CZIF2 is essential was resolved genetically: single knockout is tolerated but the double knockout with Pfczif1 cannot be achieved, establishing functional redundancy in which at least one of the two paralogs is required for growth.\",\n      \"evidence\": \"Gene knockout with growth assays and an attempted double knockout in P. falciparum\",\n      \"pmids\": [\"36400305\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"The shared molecular activity that makes the pair collectively essential is unknown\",\n        \"Whether CZIF1 and CZIF2 act on the same targets is not directly demonstrated\",\n        \"Failure to obtain the double knockout is inferred essentiality, not a conditional-depletion phenotype\"\n      ],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Assigning a downstream role, C-terminal truncation altered expression of exported proteins including PfKAHRP, linking CZIF2 to regulation of the export program rather than to invasion.\",\n      \"evidence\": \"C-terminal truncation mutagenesis combined with RNA-seq transcriptomic analysis in P. falciparum\",\n      \"pmids\": [\"36400305\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Whether CZIF2 regulates exported-protein genes directly or indirectly is not established\",\n        \"No RNA or protein target of the zinc finger domain has been identified\",\n        \"The mechanism by which the C-terminus contributes to this regulation is unresolved\"\n      ],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The molecular mechanism by which CZIF2 regulates exported protein expression, and whether it acts as an RNA-binding regulator via its C3H1 zinc finger, remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"No direct RNA or protein targets identified\",\n        \"No biochemical demonstration of nucleic-acid binding by CZIF2\",\n        \"Relationship between CZIF2 and PfCZIF1 at the molecular level uncharacterized\"\n      ],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [],\n    \"localization\": [\n      {\"term_id\": \"peripheral cytosolic foci (membrane-associated)\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"regulation of protein export to host red blood cell\", \"supporting_discovery_ids\": [2]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"PfCZIF1 (functional redundancy; not a demonstrated physical interaction)\"],\n    \"other_free_text\": [\n      \"C3H1-type zinc finger protein with peak expression during late schizogony of blood stages [#3].\",\n      \"Individually dispensable for blood-stage growth; essential only in combination with PfCZIF1 [#1].\",\n      \"C-terminal truncation alters expression of exported proteins including PfKAHRP [#2].\"\n    ]\n  }\n}","audit_flag":null,"strains":[{"strain":"Pf3D7","gene_id":"PF3D7_0818100","name":null,"product":"C3H1-type zinc finger protein CZIF2","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PbANKA","gene_id":"PBANKA_0712700","name":null,"product":"zinc finger protein, putative","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PkH","gene_id":"PKNH_0501900","name":null,"product":"zinc finger protein, putative","uniprot_acc":null,"chromosome":null,"start_pos":null}],"gene_symbol":"CZIF2","evaluation":null}