{"id":"158f225a-3554-5a1b-9f39-5df5d304b469","stable_key":"4d8e4781-3878-5818-8d0a-7dbd6e024555:chromium-transferrin-crystal","predicate":"binds","statement":"Cr(III)-transferrin crystals contained a chromium-loaded closed C-terminal lobe and an open empty N-terminal lobe; two tyrosines, histidine, aspartate and chelating malonate coordinated the metal.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"context_dependent","is_public":true,"mechanism_event_id":"f8715d4a-e73f-5c20-bd97-000196975f5a","mechanism_event_label":"The iron-carrier protein can bind chromium in a structurally characterized pocket.","subject":{"id":"ac656bc2-967c-568b-b6d5-58c7ff433c94","slug":"tf","display_name":"Human serum transferrin / TF","entity_type_key":"protein"},"object":{"id":"2d160bdf-c463-5f93-9e50-137f41a1f369","slug":"chromium-iii","display_name":"Trivalent chromium / Cr(III)","entity_type_key":"ion"},"evidence_count":1,"mechanism_event":{"id":"f8715d4a-e73f-5c20-bd97-000196975f5a","stable_key":"4d8e4781-3878-5818-8d0a-7dbd6e024555:chromium-transferrin-crystal-event","event_type":"biochemical_relationship","label":"The iron-carrier protein can bind chromium in a structurally characterized pocket.","description":"Cr(III)-transferrin crystals contained a chromium-loaded closed C-terminal lobe and an open empty N-terminal lobe; two tyrosines, histidine, aspartate and chelating malonate coordinated the metal.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"c6476f4d-d5f7-5a67-ae1f-661a7f3d8a14","slug":"human-chromium-loaded-transferrin","display_name":"Human chromium(III)-loaded transferrin","entity_type_key":"protein_state"},"role":"product_state","stoichiometry":null,"state_label":"","sequence_order":0,"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":1,"notes":""},{"entity":{"id":"2d160bdf-c463-5f93-9e50-137f41a1f369","slug":"chromium-iii","display_name":"Trivalent chromium / Cr(III)","entity_type_key":"ion"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""}]},"contexts":[{"dimension":"evidence_span","value_text":"{\"source_cache\": \"artifacts/chromium-research/32650146.abstract.txt\", \"locator\": \"Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets\", \"file_sha256\": \"826e2d7f86ec2016d526ca8a8858db0249f4797aad842189d7f0359b6f375f85\", \"start_char\": 0, \"end_char\": 1004, \"text_sha256\": \"826e2d7f86ec2016d526ca8a8858db0249f4797aad842189d7f0359b6f375f85\"}","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"X-ray crystallography of chromium-loaded transferrin","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"Cr(III)-transferrin crystallized with malonate as the synergistic anion","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Crystal ligands and occupancy depend on preparation; malonate is not evidence that every circulating complex has the same coordination environment.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Chromium research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"chromium","display_name":"Chromium","entity_type_key":"nutrient_element"}},{"dimension":"organism","value_text":"Human serum transferrin","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"The iron-carrier protein can bind chromium in a structurally characterized pocket.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[chromium-p32650146] X-ray structure of chromium(III)-containing transferrin: First structure of a physiological Cr(III)-binding protein. (2020). https://pubmed.ncbi.nlm.nih.gov/32650146/ DOI: 10.1016/j.jinorgbio.2020.111101","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Protein crystals","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"13df716f-4069-5e2d-9a79-b1129a91363b","evidence_kind":"source_excerpt","locator":"Lines 146-157","start_line":146,"end_line":157,"excerpt":"### chromium-transferrin-crystal\nCr(III)-transferrin crystals contained a chromium-loaded closed C-terminal lobe and an open empty N-terminal lobe; two tyrosines, histidine, aspartate and chelating malonate coordinated the metal.\nCondition category: normal\nnutrient_topic: Chromium research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: The iron-carrier protein can bind chromium in a structurally characterized pocket.\norganism: Human serum transferrin\ntissue_or_cell_type: Protein crystals\nexperimental_model: X-ray crystallography of chromium-loaded transferrin\nlimitations: Crystal ligands and occupancy depend on preparation; malonate is not evidence that every circulating complex has the same coordination environment.\nexposure: Cr(III)-transferrin crystallized with malonate as the synergistic anion\nevidence_span: {\"source_cache\": \"artifacts/chromium-research/32650146.abstract.txt\", \"locator\": \"Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets\", \"file_sha256\": \"826e2d7f86ec2016d526ca8a8858db0249f4797aad842189d7f0359b6f375f85\", \"start_char\": 0, \"end_char\": 1004, \"text_sha256\": \"826e2d7f86ec2016d526ca8a8858db0249f4797aad842189d7f0359b6f375f85\"}\n[chromium-p32650146] X-ray structure of chromium(III)-containing transferrin: First structure of a physiological Cr(III)-binding protein. (2020). https://pubmed.ncbi.nlm.nih.gov/32650146/ DOI: 10.1016/j.jinorgbio.2020.111101","model_system":"X-ray crystallography of chromium-loaded transferrin","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [chromium-p32650146] X-ray structure of chromium(III)-containing transferrin: First structure of a physiological Cr(III)-binding protein. (2020). https://pubmed.ncbi.nlm.nih.gov/32650146/ DOI: 10.1016/j.jinorgbio.2020.111101","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"fa96342a-ca01-5425-98d9-d50e29bf0abd","stable_key":"import-4d8e4781-3878-5818-8d0a-7dbd6e024555","title":"Chromium: transport, insulin signaling, nutrient interactions and essentiality debate (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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