{"id":"922d4ad1-50ce-549b-8694-16105604d78b","stable_key":"cfa4bd86-d88d-555a-975c-68877bf00e0f:lutein-bco2-targeting","predicate":"targets_to","statement":"The BCO2a targeting sequence directed a reporter to mitochondria in ARPE-19 cells; this experiment establishes mitochondrial import, not precise membrane topology.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"context_dependent","is_public":true,"mechanism_event_id":"9cb5ae02-c8e4-50e7-90e3-dc4834b7983b","mechanism_event_label":"An amino-terminal address directs the protein into mitochondria.","subject":{"id":"df3b7ead-aeb7-56b9-8274-312d010df47a","slug":"human-bco2a","display_name":"Human BCO2a precursor isoform","entity_type_key":"protein"},"object":{"id":"f5bd4edd-4298-5985-976f-897fd415c3d5","slug":"mitochondria","display_name":"Mitochondria","entity_type_key":"organelle"},"evidence_count":1,"mechanism_event":{"id":"9cb5ae02-c8e4-50e7-90e3-dc4834b7983b","stable_key":"cfa4bd86-d88d-555a-975c-68877bf00e0f:lutein-bco2-targeting-event","event_type":"biochemical_relationship","label":"An amino-terminal address directs the protein into mitochondria.","description":"The BCO2a targeting sequence directed a reporter to mitochondria in ARPE-19 cells; this experiment establishes mitochondrial import, not precise membrane topology.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"df3b7ead-aeb7-56b9-8274-312d010df47a","slug":"human-bco2a","display_name":"Human BCO2a precursor isoform","entity_type_key":"protein"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"f5bd4edd-4298-5985-976f-897fd415c3d5","slug":"mitochondria","display_name":"Mitochondria","entity_type_key":"organelle"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""}]},"contexts":[{"dimension":"evidence_span","value_text":"{\"source_cache\": \"artifacts/lutein-research/32873706.abstract.txt\", \"locator\": \"Primary indexed abstract; zero-based, end-exclusive Unicode character offsets\", \"file_sha256\": \"1555914c4a5090c968595f2aba72ce276054594a66423916be600a600a28349f\", \"start_char\": 0, \"end_char\": 1517, \"text_sha256\": \"1555914c4a5090c968595f2aba72ce276054594a66423916be600a600a28349f\"}","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Isoform targeting, recombinant expression and enzyme assays","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"Removal of N-terminal mitochondrial targeting sequence; expression optimization","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Activity of processed recombinant protein does not quantify retinal flux; mouse chimeric substrate results remain mouse-specific.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Lutein research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"lutein","display_name":"Lutein","entity_type_key":"small_molecule"}},{"dimension":"organism","value_text":"Human BCO2 isoforms and engineered mouse protein","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"An amino-terminal address directs the protein into mitochondria.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[lutein-p32873706] The human mitochondrial enzyme BCO2 exhibits catalytic activity toward carotenoids and apocarotenoids. 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