{"id":"79bce51c-8104-5c36-bb32-83949cb569a7","stable_key":"e13b03e1-a614-543a-ac1b-97df18cfe30d:iron-tf-acidic-release","predicate":"releases_iron_during","statement":"The transferrin-cycle model supported by the binding experiments releases iron in acidified endosomes while apotransferrin remains receptor-bound.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"context_dependent","is_public":true,"mechanism_event_id":"3982b68f-1d91-5fe8-b7ef-e7c4d97adaee","mechanism_event_label":"The carrier gives up its iron inside an acidic compartment but stays attached to its return transport.","subject":{"id":"ac656bc2-967c-568b-b6d5-58c7ff433c94","slug":"tf","display_name":"Human serum transferrin / TF","entity_type_key":"protein"},"object":{"id":"d4d69860-dd2e-51af-8924-53fcb9c9977a","slug":"endosomal-iron-release","display_name":"Transferrin-dependent endosomal iron delivery to cytosol","entity_type_key":"cellular_process"},"evidence_count":1,"mechanism_event":{"id":"3982b68f-1d91-5fe8-b7ef-e7c4d97adaee","stable_key":"e13b03e1-a614-543a-ac1b-97df18cfe30d:iron-tf-acidic-release-event","event_type":"biochemical_relationship","label":"The carrier gives up its iron inside an acidic compartment but stays attached to its return transport.","description":"The transferrin-cycle model supported by the binding experiments releases iron in acidified endosomes while apotransferrin remains receptor-bound.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"05415b89-a435-5940-a9ba-b587a0b6f04d","slug":"tfrc","display_name":"Human transferrin receptor 1 / TFRC","entity_type_key":"protein"},"role":"receptor","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"964be7ac-43bd-5f3e-8326-94f0590de67a","slug":"iron-iii","display_name":"Ferric iron","entity_type_key":"ion"},"role":"transferrin_bound_metal","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"ac656bc2-967c-568b-b6d5-58c7ff433c94","slug":"tf","display_name":"Human serum transferrin / TF","entity_type_key":"protein"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""},{"entity":{"id":"d4d69860-dd2e-51af-8924-53fcb9c9977a","slug":"endosomal-iron-release","display_name":"Transferrin-dependent endosomal iron delivery to cytosol","entity_type_key":"cellular_process"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":3,"notes":""}]},"contexts":[{"dimension":"evidence_span","value_text":"{\"source_cache\": \"artifacts/iron-research/6300903.abstract.txt\", \"locator\": \"Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets\", \"file_sha256\": \"29d23cdaaacd30003c1f3e70935d7ab5ccbb1612379d6e650d356d1235438852\", \"start_char\": 0, \"end_char\": 906, \"text_sha256\": \"29d23cdaaacd30003c1f3e70935d7ab5ccbb1612379d6e650d356d1235438852\"}","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Receptor binding at controlled pH and transferrin cycle analysis","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"Apotransferrin and diferric transferrin binding at acidic versus neutral pH","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"The indexed abstract does not identify the cell line; its experiments support a pH-dependent trafficking model, not direct measures of whole-body iron turnover.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Iron research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"iron","display_name":"Iron","entity_type_key":"nutrient_element"}},{"dimension":"organism","value_text":"Cultured-cell transferrin receptor system","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"The carrier gives up its iron inside an acidic compartment but stays attached to its return transport.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[iron-p6300903] pH and the recycling of transferrin during receptor-mediated endocytosis. (1983). https://pubmed.ncbi.nlm.nih.gov/6300903/ DOI: 10.1073/pnas.80.8.2258","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Cell surface and endosomal recycling model","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"8047c6b3-8e4c-5c3e-8c4e-1988d045ae51","evidence_kind":"source_excerpt","locator":"Lines 420-431","start_line":420,"end_line":431,"excerpt":"### iron-tf-acidic-release\nThe transferrin-cycle model supported by the binding experiments releases iron in acidified endosomes while apotransferrin remains receptor-bound.\nCondition category: normal\nnutrient_topic: Iron research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: The carrier gives up its iron inside an acidic compartment but stays attached to its return transport.\norganism: Cultured-cell transferrin receptor system\ntissue_or_cell_type: Cell surface and endosomal recycling model\nexperimental_model: Receptor binding at controlled pH and transferrin cycle analysis\nlimitations: The indexed abstract does not identify the cell line; its experiments support a pH-dependent trafficking model, not direct measures of whole-body iron turnover.\nexposure: Apotransferrin and diferric transferrin binding at acidic versus neutral pH\nevidence_span: {\"source_cache\": \"artifacts/iron-research/6300903.abstract.txt\", \"locator\": \"Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets\", \"file_sha256\": \"29d23cdaaacd30003c1f3e70935d7ab5ccbb1612379d6e650d356d1235438852\", \"start_char\": 0, \"end_char\": 906, \"text_sha256\": \"29d23cdaaacd30003c1f3e70935d7ab5ccbb1612379d6e650d356d1235438852\"}\n[iron-p6300903] pH and the recycling of transferrin during receptor-mediated endocytosis. (1983). https://pubmed.ncbi.nlm.nih.gov/6300903/ DOI: 10.1073/pnas.80.8.2258","model_system":"Receptor binding at controlled pH and transferrin cycle analysis","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [iron-p6300903] pH and the recycling of transferrin during receptor-mediated endocytosis. (1983). https://pubmed.ncbi.nlm.nih.gov/6300903/ DOI: 10.1073/pnas.80.8.2258","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"1560864c-91d1-58dc-90c4-49bf61aba3de","stable_key":"import-e13b03e1-a614-543a-ac1b-97df18cfe30d","title":"Iron: absorption, trafficking, iron-dependent enzymes and nutrient interactions (2026-09-17)","document_type":"imported_text","citation_label":"AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text.","file_path":"","sha256":"f9dab767a21c9bbfef3227707fe3c82953536bb1335599dd4ef93b5ea2dbf03f","revision_id":"77700d7f-2902-54b9-adae-8cbc77b24682","review_status":"unverified_draft","notes":""}}],"relations":[],"conflicts":[],"corrections":[],"research":null}