{"gene":"TG_500245","gene_symbol":"RDF2","run_date":"2026-09-08T16:10:21","timeline":{"discoveries":[{"year":2022,"finding":"RDF2 (previously annotated as MIC14) is a thrombospondin-related protein exclusive to the Coccidia class of apicomplexans, possessing a C-terminal transmembrane domain followed by a short cytoplasmic tail, with a paralogous relationship to RDF1.","method":"Sequence analysis and immunofluorescence analysis of T. gondii tachyzoites","journal":"Frontiers in microbiology","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — structural/sequence characterization combined with immunofluorescence, single lab, but protein was not detected by immunofluorescence under normal conditions","pmids":["35756016"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2022,"finding":"RDF2 expression is spontaneously upregulated in parasites subjected to conditional knockdown of the paralog RDF1, and this compensatory upregulation rescues rhoptry discharge, demonstrating that RDF2 can functionally substitute for RDF1 in the rhoptry exocytosis pathway.","method":"Conditional knockdown (inducible repression) of RDF1 with monitoring of RDF2 gene expression and rhoptry secretion assays","journal":"Frontiers in microbiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — conditional KD with defined phenotypic readout (rhoptry discharge) and compensatory upregulation shown, single lab","pmids":["35756016"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]}],"current_model":"RDF2 is a Coccidia-specific thrombospondin-related transmembrane protein that functions as a key player in the rhoptry exocytosis pathway in Toxoplasma gondii, capable of compensating for loss of its paralog RDF1 to rescue rhoptry discharge and thereby host cell invasion."},"narrative":{"mechanistic_narrative":"RDF2 (formerly annotated MIC14) is a thrombospondin-related transmembrane protein restricted to the Coccidia class of apicomplexans and paralogous to RDF1, comprising a C-terminal transmembrane domain followed by a short cytoplasmic tail [PMID:35756016]. It participates in the rhoptry exocytosis pathway of Toxoplasma gondii: upon conditional knockdown of RDF1, RDF2 is spontaneously upregulated, and this compensatory expression restores rhoptry discharge, establishing that RDF2 can functionally substitute for RDF1 in driving rhoptry secretion [PMID:35756016]. Beyond this compensatory role in rhoptry discharge, no further mechanistic detail — including its molecular binding partners, the structural basis of its activity, or its behavior under normal expression conditions — has been characterized in the available corpus.","teleology":[{"year":2022,"claim":"Establishing that RDF2 is a distinct Coccidia-specific protein with a defined membrane topology and a paralogous relationship to RDF1 provided the structural framework for asking whether the two proteins share function.","evidence":"Sequence analysis and immunofluorescence of T. gondii tachyzoites","pmids":["35756016"],"confidence":"Medium","gaps":["Protein was not detected by immunofluorescence under normal conditions, leaving its native localization unresolved","No binding partners or substrates identified","No structural model of the thrombospondin-related domain or cytoplasmic tail"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2022,"claim":"Testing whether RDF2 has a role in rhoptry secretion showed that it is spontaneously upregulated upon RDF1 knockdown and rescues rhoptry discharge, establishing functional redundancy between the paralogs in the rhoptry exocytosis pathway.","evidence":"Conditional knockdown of RDF1 with RDF2 expression monitoring and rhoptry secretion assays in T. gondii","pmids":["35756016"],"confidence":"Medium","gaps":["Mechanism by which RDF2 promotes rhoptry discharge is unknown","The trigger for compensatory upregulation of RDF2 is uncharacterized","Whether RDF2 has a non-redundant function under normal RDF1 expression is unresolved"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":null,"claim":"The molecular mechanism by which RDF2 acts in rhoptry exocytosis — its interaction partners, the role of its transmembrane and cytoplasmic domains, and its function under native conditions — remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No molecular partners in the rhoptry discharge machinery identified","No functional dissection of the transmembrane domain or cytoplasmic tail","Native expression, localization, and non-redundant role undefined"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]}],"mechanism_profile":{"molecular_activity":[],"localization":[],"pathway":[],"complexes":[],"partners":["RDF1 (PARALOG; FUNCTIONALLY REDUNDANT IN RHOPTRY DISCHARGE)"],"other_free_text":["Thrombospondin-related transmembrane protein with a C-terminal transmembrane domain and short cytoplasmic tail, exclusive to the Coccidia class of apicomplexans [#0]","Compensatory upregulation of RDF2 upon RDF1 knockdown rescues rhoptry discharge, indicating functional substitution within the rhoptry exocytosis pathway [#1]"]},"strain_conflicts":[]},"prefetch_data":{},"corpus_meta":[{"pmid":"35756016","id":"PMC_35756016","title":"Functional Characterization of the Thrombospondin-Related Paralogous Proteins Rhoptry Discharge Factors 1 and 2 Unveils Phenotypic Plasticity in Toxoplasma gondii Rhoptry Exocytosis.","date":"2022","source":"Frontiers in microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/35756016","citation_count":11,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":3088,"output_tokens":577,"usd":0.00896,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":5284,"output_tokens":1515,"usd":0.032148,"stage2_stop_reason":"end_turn"},"total_usd":0.041108,"stage1_batch_id":"msgbatch_01RQGfcbGqQD3GfCPaX8jpfW","stage2_batch_id":"msgbatch_019PABGEC4M9vU7v6jy6Fvwg","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2022,\n      \"finding\": \"RDF2 (previously annotated as MIC14) is a thrombospondin-related protein exclusive to the Coccidia class of apicomplexans, possessing a C-terminal transmembrane domain followed by a short cytoplasmic tail, with a paralogous relationship to RDF1.\",\n      \"method\": \"Sequence analysis and immunofluorescence analysis of T. gondii tachyzoites\",\n      \"journal\": \"Frontiers in microbiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — structural/sequence characterization combined with immunofluorescence, single lab, but protein was not detected by immunofluorescence under normal conditions\",\n      \"pmids\": [\"35756016\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"RDF2 expression is spontaneously upregulated in parasites subjected to conditional knockdown of the paralog RDF1, and this compensatory upregulation rescues rhoptry discharge, demonstrating that RDF2 can functionally substitute for RDF1 in the rhoptry exocytosis pathway.\",\n      \"method\": \"Conditional knockdown (inducible repression) of RDF1 with monitoring of RDF2 gene expression and rhoptry secretion assays\",\n      \"journal\": \"Frontiers in microbiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — conditional KD with defined phenotypic readout (rhoptry discharge) and compensatory upregulation shown, single lab\",\n      \"pmids\": [\"35756016\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    }\n  ],\n  \"current_model\": \"RDF2 is a Coccidia-specific thrombospondin-related transmembrane protein that functions as a key player in the rhoptry exocytosis pathway in Toxoplasma gondii, capable of compensating for loss of its paralog RDF1 to rescue rhoptry discharge and thereby host cell invasion.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"RDF2 (formerly annotated MIC14) is a thrombospondin-related transmembrane protein restricted to the Coccidia class of apicomplexans and paralogous to RDF1, comprising a C-terminal transmembrane domain followed by a short cytoplasmic tail [#0]. It participates in the rhoptry exocytosis pathway of Toxoplasma gondii: upon conditional knockdown of RDF1, RDF2 is spontaneously upregulated, and this compensatory expression restores rhoptry discharge, establishing that RDF2 can functionally substitute for RDF1 in driving rhoptry secretion [#1]. Beyond this compensatory role in rhoptry discharge, no further mechanistic detail — including its molecular binding partners, the structural basis of its activity, or its behavior under normal expression conditions — has been characterized in the available corpus.\",\n  \"teleology\": [\n    {\n      \"year\": 2022,\n      \"claim\": \"Establishing that RDF2 is a distinct Coccidia-specific protein with a defined membrane topology and a paralogous relationship to RDF1 provided the structural framework for asking whether the two proteins share function.\",\n      \"evidence\": \"Sequence analysis and immunofluorescence of T. gondii tachyzoites\",\n      \"pmids\": [\"35756016\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Protein was not detected by immunofluorescence under normal conditions, leaving its native localization unresolved\",\n        \"No binding partners or substrates identified\",\n        \"No structural model of the thrombospondin-related domain or cytoplasmic tail\"\n      ],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Testing whether RDF2 has a role in rhoptry secretion showed that it is spontaneously upregulated upon RDF1 knockdown and rescues rhoptry discharge, establishing functional redundancy between the paralogs in the rhoptry exocytosis pathway.\",\n      \"evidence\": \"Conditional knockdown of RDF1 with RDF2 expression monitoring and rhoptry secretion assays in T. gondii\",\n      \"pmids\": [\"35756016\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Mechanism by which RDF2 promotes rhoptry discharge is unknown\",\n        \"The trigger for compensatory upregulation of RDF2 is uncharacterized\",\n        \"Whether RDF2 has a non-redundant function under normal RDF1 expression is unresolved\"\n      ],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The molecular mechanism by which RDF2 acts in rhoptry exocytosis — its interaction partners, the role of its transmembrane and cytoplasmic domains, and its function under native conditions — remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"No molecular partners in the rhoptry discharge machinery identified\",\n        \"No functional dissection of the transmembrane domain or cytoplasmic tail\",\n        \"Native expression, localization, and non-redundant role undefined\"\n      ],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [],\n    \"localization\": [],\n    \"pathway\": [\n      {\"term_id\": \"rhoptry exocytosis / rhoptry discharge\", \"supporting_discovery_ids\": [1], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"RDF1 (paralog; functionally redundant in rhoptry discharge)\"],\n    \"other_free_text\": [\n      \"Thrombospondin-related transmembrane protein with a C-terminal transmembrane domain and short cytoplasmic tail, exclusive to the Coccidia class of apicomplexans [#0]\",\n      \"Compensatory upregulation of RDF2 upon RDF1 knockdown rescues rhoptry discharge, indicating functional substitution within the rhoptry exocytosis pathway [#1]\"\n    ]\n  },\n  \"strain_conflicts\": []\n}\n```","audit_flag":null,"strains":[{"strain":"ME49","gene_id":"TGME49_500245","name":"RDF2","product":"rhoptry discharge factor RDF2","uniprot_acc":"S8ER04","chromosome":"TGME49_chrXII","start_pos":1578035},{"strain":"GT1","gene_id":"TGGT1_218310","name":null,"product":"microneme protein MIC14","uniprot_acc":null,"chromosome":"TGGT1_chrXII","start_pos":1537308},{"strain":"RH88","gene_id":"TGRH88_059040","name":null,"product":"microneme protein MIC14","uniprot_acc":null,"chromosome":"CM023093","start_pos":1596673},{"strain":"VEG","gene_id":"TGVEG_218310","name":null,"product":"microneme protein MIC14","uniprot_acc":"B9PQE4","chromosome":"TGVEG_chrXII","start_pos":1570463}]}