{"id":"9e336345-028c-5acf-a294-7df86b4a4034","stable_key":"3c852f36-7951-5fd9-9013-d771a8d16d8a:vae-rgr-dark-chromophore","predicate":"binds","statement":"RGR purified from bovine RPE contained predominantly all-trans-retinal as its endogenous dark-state chromophore.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"positive","is_public":true,"mechanism_event_id":"de011b6f-8b60-5eae-bbad-b72ae5dbd595","mechanism_event_label":"RGR carries the spent all-trans retinal isomer before light reaches it.","subject":{"id":"205eda81-4688-5fa3-a08c-e94d0c1cbf5c","slug":"rgr","display_name":"Retinal G protein-coupled receptor / RGR opsin","entity_type_key":"protein"},"object":{"id":"194eccf2-c7a5-52a6-a0c6-1c1f6d0f3a3e","slug":"all-trans-retinal","display_name":"All-trans-retinal","entity_type_key":"small_molecule"},"evidence_count":1,"mechanism_event":{"id":"de011b6f-8b60-5eae-bbad-b72ae5dbd595","stable_key":"3c852f36-7951-5fd9-9013-d771a8d16d8a:vae-rgr-dark-chromophore-event","event_type":"biochemical_relationship","label":"RGR carries the spent all-trans retinal isomer before light reaches it.","description":"RGR purified from bovine RPE contained predominantly all-trans-retinal as its endogenous dark-state chromophore.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"205eda81-4688-5fa3-a08c-e94d0c1cbf5c","slug":"rgr","display_name":"Retinal G protein-coupled receptor / RGR opsin","entity_type_key":"protein"},"role":"retinal-binding protein","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"194eccf2-c7a5-52a6-a0c6-1c1f6d0f3a3e","slug":"all-trans-retinal","display_name":"All-trans-retinal","entity_type_key":"small_molecule"},"role":"bound chromophore","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""}]},"contexts":[{"dimension":"cross_nutrient","value_text":"false","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"evidence_location","value_text":"Abstract: endogenous retinaloxime isomers","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Native RGR purification and hydroxylamine derivatization","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"Dark-handled purified protein; retinal-oxime isomers identified.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Abstract-limited; binding composition does not quantify whole-eye recycling.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient","value_text":"Vitamin A","comparator":null,"unit":null,"notes":"","entity":{"slug":"vitamin-a","display_name":"Vitamin A","entity_type_key":"chemical_species"}},{"dimension":"nutrient_topic","value_text":"Vitamin A expansion research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"vitamin-a","display_name":"Vitamin A","entity_type_key":"chemical_species"}},{"dimension":"organism","value_text":"Bos taurus","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"RGR carries the spent all-trans retinal isomer before light reaches it.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[vav-hao1999] The endogenous chromophore of retinal G protein-coupled receptor opsin from the pigment epithelium. (1999). https://pubmed.ncbi.nlm.nih.gov/10037690/ DOI: 10.1074/jbc.274.10.6085","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"retinal pigment epithelium","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"2ad84803-c56a-5b02-81b4-a5381392f543","evidence_kind":"source_excerpt","locator":"Lines 408-421","start_line":408,"end_line":421,"excerpt":"### vae-rgr-dark-chromophore\nRGR purified from bovine RPE contained predominantly all-trans-retinal as its endogenous dark-state chromophore.\nCondition category: normal\nnutrient_topic: Vitamin A expansion research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: RGR carries the spent all-trans retinal isomer before light reaches it.\norganism: Bos taurus\ntissue_or_cell_type: retinal pigment epithelium\nexperimental_model: Native RGR purification and hydroxylamine derivatization\nlimitations: Abstract-limited; binding composition does not quantify whole-eye recycling.\nexposure: Dark-handled purified protein; retinal-oxime isomers identified.\ncross_nutrient: false\nevidence_location: Abstract: endogenous retinaloxime isomers\nnutrient: Vitamin A\n[vav-hao1999] The endogenous chromophore of retinal G protein-coupled receptor opsin from the pigment epithelium. (1999). https://pubmed.ncbi.nlm.nih.gov/10037690/ DOI: 10.1074/jbc.274.10.6085","model_system":"Native RGR purification and hydroxylamine derivatization","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [vav-hao1999] The endogenous chromophore of retinal G protein-coupled receptor opsin from the pigment epithelium. (1999). https://pubmed.ncbi.nlm.nih.gov/10037690/ DOI: 10.1074/jbc.274.10.6085","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"83131a07-353f-5301-9ce6-50754c194952","stable_key":"import-3c852f36-7951-5fd9-9013-d771a8d16d8a","title":"Vitamin A expansion: reproduction, light-driven vision and shared mechanisms (2026-09-17)","document_type":"imported_text","citation_label":"AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. 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