{"id":"99a791e7-3ef9-51f2-9304-71541a6dbc19","stable_key":"research:sephs2-selenium-donor-supply","predicate":"supports_supply_of","statement":"SEPHS2 supplies the activated selenium donor used for Sec-tRNA synthesis; mammalian loss/rescue experiments establish its biosynthetic requirement.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"literature_reviewed:supported_interpretation","direction":"positive","is_public":true,"mechanism_event_id":"ce594443-c465-5d6c-a95f-dcffb384d396","mechanism_event_label":"SEPHS2 prepares selenium for the machinery that builds selenoproteins.","subject":{"id":"e4617b6f-3a5d-5ea4-841f-bfa2f9ca18bc","slug":"sephs2","display_name":"SEPHS2","entity_type_key":"protein"},"object":{"id":"f997135c-327f-5eb7-b159-1f046d14d4c2","slug":"selenophosphate","display_name":"Selenophosphate","entity_type_key":"chemical_species"},"evidence_count":1,"mechanism_event":{"id":"ce594443-c465-5d6c-a95f-dcffb384d396","stable_key":"research:sephs2-selenium-donor-supply","event_type":"experimentally_scoped_interaction","label":"SEPHS2 prepares selenium for the machinery that builds selenoproteins.","description":"SEPHS2 supplies the activated selenium donor used for Sec-tRNA synthesis; mammalian loss/rescue experiments establish its biosynthetic requirement.","status":"active","compartment":null,"participants":[{"entity":{"id":"e4617b6f-3a5d-5ea4-841f-bfa2f9ca18bc","slug":"sephs2","display_name":"SEPHS2","entity_type_key":"protein"},"role":"regulator","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"f997135c-327f-5eb7-b159-1f046d14d4c2","slug":"selenophosphate","display_name":"Selenophosphate","entity_type_key":"chemical_species"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""}]},"contexts":[{"dimension":"experimental_model","value_text":"Mammalian cell knockdown/rescue and selenoprotein synthesis assays.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Requirement for biosynthesis does not prove that SEPHS2 is always the last selenoprotein preserved during dietary restriction.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"organism","value_text":"Mammalian cultured cells","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"ef03078f-b1f3-58c2-a770-14d4238affe1","evidence_kind":"curated_literature_summary","locator":"lines 1119-1128","start_line":1119,"end_line":1128,"excerpt":"## sephs2-selenium-donor-supply\n\nSEPHS2 prepares selenium for the machinery that builds selenoproteins.\n\nSEPHS2 supplies the activated selenium donor used for Sec-tRNA synthesis; mammalian loss/rescue experiments establish its biosynthetic requirement.\n\nExperimental model: Mammalian cell knockdown/rescue and selenoprotein synthesis assays.\nOrganism: Mammalian cultured cells\nLimitations: Requirement for biosynthesis does not prove that SEPHS2 is always the last selenoprotein preserved during dietary restriction.\nPrimary reference: [Selenophosphate synthetase 2 is essential for selenoprotein biosynthesis](https://pmc.ncbi.nlm.nih.gov/articles/PMC1868833/)","model_system":"Mammalian cell knockdown/rescue and selenoprotein synthesis assays.","directness":"author_interpretation","verification_status":"secondary_verified","notes":"Curated summary; inspect the linked primary papers for original methods and results.","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"4f892f13-06ea-5199-a33c-a703f35c80ae","stable_key":"selenium-research-2026-09-17","title":"Selenium: literature corrections and mechanism additions","document_type":"curated_literature_review","citation_label":"Metabolic Ledger literature curation, 17 September 2026; primary papers linked individually","file_path":"","sha256":"0b818b10c1c7120e5caf7f4d4019d7bd025d745692e424f515d3ef903c9ab7f3","revision_id":"80984e03-5f0f-5877-8094-afef7637444e","review_status":"secondary_verified","notes":"Secondary curated summaries of primary experiments, with explicit models and limitations. Not archived primary full text."}}],"relations":[],"conflicts":[],"corrections":[],"research":{"topic":"Selenoprotein synthesis","plain_language":"SEPHS2 prepares selenium for the machinery that builds selenoproteins.","evidence_scope":"supported_interpretation","papers":[{"key":"catalog-sephs2-2007","title":"Selenophosphate synthetase 2 is essential for selenoprotein biosynthesis","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC1868833/","doi":null,"year":2007,"model":"Mammalian cell knockdown/rescue and selenoprotein synthesis assays.","summary":"Distinguishes the essential selenium-donor-supply role of SEPHS2 from the homologous SEPHS1 protein."}]}}