{"id":"aaad5006-f55c-5c0e-9022-e347cb3fcdf9","stable_key":"e13b03e1-a614-543a-ac1b-97df18cfe30d:iron-tf-recycling","predicate":"supports","statement":"Apotransferrin bound receptors at pH 5.4 but dissociated rapidly when pH was raised to 7.0.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"context_dependent","is_public":true,"mechanism_event_id":"3504fca2-2f85-5e94-a07c-f9a7c4efed84","mechanism_event_label":"Returning to the neutral cell surface allows the empty carrier to detach.","subject":{"id":"05415b89-a435-5940-a9ba-b587a0b6f04d","slug":"tfrc","display_name":"Human transferrin receptor 1 / TFRC","entity_type_key":"protein"},"object":{"id":"540ab8bf-a6d4-5b5e-88ac-2a5df4f3f31c","slug":"transferrin-receptor-recycling","display_name":"Transferrin and transferrin-receptor recycling","entity_type_key":"cellular_process"},"evidence_count":1,"mechanism_event":{"id":"3504fca2-2f85-5e94-a07c-f9a7c4efed84","stable_key":"e13b03e1-a614-543a-ac1b-97df18cfe30d:iron-tf-recycling-event","event_type":"biochemical_relationship","label":"Returning to the neutral cell surface allows the empty carrier to detach.","description":"Apotransferrin bound receptors at pH 5.4 but dissociated rapidly when pH was raised to 7.0.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"ac656bc2-967c-568b-b6d5-58c7ff433c94","slug":"tf","display_name":"Human serum transferrin / TF","entity_type_key":"protein"},"role":"recycled_carrier","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"05415b89-a435-5940-a9ba-b587a0b6f04d","slug":"tfrc","display_name":"Human transferrin receptor 1 / TFRC","entity_type_key":"protein"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"540ab8bf-a6d4-5b5e-88ac-2a5df4f3f31c","slug":"transferrin-receptor-recycling","display_name":"Transferrin and transferrin-receptor recycling","entity_type_key":"cellular_process"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":2,"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":"Returning to the neutral cell surface allows the empty carrier to detach.","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":"4e28bd18-8473-5bfd-a1c0-a31658daf638","evidence_kind":"source_excerpt","locator":"Lines 433-444","start_line":433,"end_line":444,"excerpt":"### iron-tf-recycling\nApotransferrin bound receptors at pH 5.4 but dissociated rapidly when pH was raised to 7.0.\nCondition category: normal\nnutrient_topic: Iron research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: Returning to the neutral cell surface allows the empty carrier to detach.\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. 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