{"id":"b61c1e0d-bf69-5aa7-957f-0e9cc11ef73c","stable_key":"7fc92b9e-9cbf-556e-8719-6b5244625250:b12-lmbd1-no-direct-transport","predicate":"does-not-detectably-transport","statement":"LMBD1-only proteoliposomes had no detectable cobalamin transport in the same reconstitution system in which ABCD4 transported cobalamin.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"neutral","is_public":true,"mechanism_event_id":"74f7e2de-97da-53da-a587-34dc579a1178","mechanism_event_label":"The escort alone did not transport B12 in this membrane assay.","subject":{"id":"3cf57c43-b33e-5c4e-a53d-dc80695775bb","slug":"lmbrd1","display_name":"Human LMBD1 lysosomal membrane protein","entity_type_key":"protein"},"object":{"id":"b6d9b937-895d-5e0a-8cc5-0454a0b7d373","slug":"vitamin-b12","display_name":"Vitamin B12 (cobalamins)","entity_type_key":"chemical_species"},"evidence_count":1,"mechanism_event":{"id":"74f7e2de-97da-53da-a587-34dc579a1178","stable_key":"7fc92b9e-9cbf-556e-8719-6b5244625250:b12-lmbd1-no-direct-transport-event","event_type":"biochemical_relationship","label":"The escort alone did not transport B12 in this membrane assay.","description":"LMBD1-only proteoliposomes had no detectable cobalamin transport in the same reconstitution system in which ABCD4 transported cobalamin.","status":"provisional","compartment":{"slug":"lysosome","display_name":"Lysosome"},"participants":[{"entity":{"id":"831afa98-dacd-516d-ae1e-680432a78525","slug":"abcd4","display_name":"Human ABCD4 lysosomal cobalamin transporter","entity_type_key":"protein"},"role":"positive transport comparator","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"3cf57c43-b33e-5c4e-a53d-dc80695775bb","slug":"lmbrd1","display_name":"Human LMBD1 lysosomal membrane protein","entity_type_key":"protein"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"b6d9b937-895d-5e0a-8cc5-0454a0b7d373","slug":"vitamin-b12","display_name":"Vitamin B12 (cobalamins)","entity_type_key":"chemical_species"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""}]},"contexts":[{"dimension":"cross_nutrient","value_text":"false","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"evidence_location","value_text":"Results: Figures 3, 4, 5; Experimental procedures: liposomes and transport assays","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Purified human ABCD4/LMBD1 in synthetic liposomes after yeast expression","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"LMBD1-only versus ABCD4-containing proteoliposomes","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Assay-specific absence of activity does not negate LMBD1’s cellular targeting role.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Vitamin B12 research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"vitamin-b12","display_name":"Vitamin B12 (cobalamins)","entity_type_key":"chemical_species"}},{"dimension":"organism","value_text":"Homo sapiens","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"The escort alone did not transport B12 in this membrane assay.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[kitai-2021-abcd4-transport] The lysosomal protein ABCD4 can transport vitamin B12 across liposomal membranes in vitro (2021). https://pubmed.ncbi.nlm.nih.gov/33845046/ DOI: 10.1016/j.jbc.2021.100654","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Cell-free membrane system","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"b6d15453-491a-5412-9dbb-8df61b989f56","evidence_kind":"source_excerpt","locator":"Lines 627-639","start_line":627,"end_line":639,"excerpt":"### b12-lmbd1-no-direct-transport\nLMBD1-only proteoliposomes had no detectable cobalamin transport in the same reconstitution system in which ABCD4 transported cobalamin.\nCondition category: normal\nnutrient_topic: Vitamin B12 research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: The escort alone did not transport B12 in this membrane assay.\norganism: Homo sapiens\ntissue_or_cell_type: Cell-free membrane system\nexperimental_model: Purified human ABCD4/LMBD1 in synthetic liposomes after yeast expression\nlimitations: Assay-specific absence of activity does not negate LMBD1’s cellular targeting role.\nexposure: LMBD1-only versus ABCD4-containing proteoliposomes\ncross_nutrient: false\nevidence_location: Results: Figures 3, 4, 5; Experimental procedures: liposomes and transport assays\n[kitai-2021-abcd4-transport] The lysosomal protein ABCD4 can transport vitamin B12 across liposomal membranes in vitro (2021). https://pubmed.ncbi.nlm.nih.gov/33845046/ DOI: 10.1016/j.jbc.2021.100654","model_system":"Purified human ABCD4/LMBD1 in synthetic liposomes after yeast expression","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [kitai-2021-abcd4-transport] The lysosomal protein ABCD4 can transport vitamin B12 across liposomal membranes in vitro (2021). https://pubmed.ncbi.nlm.nih.gov/33845046/ DOI: 10.1016/j.jbc.2021.100654","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"73145023-2982-5848-aff2-8d8875d6b9c5","stable_key":"import-7fc92b9e-9cbf-556e-8719-6b5244625250","title":"Vitamin B12: mechanisms, deficiency 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":"ad5b3a51d36e856aa7fdfd1cc23f690b094689bad87d28e1a621a54675a01c92","revision_id":"118bd616-0c13-549f-bfeb-bc439715b89c","review_status":"unverified_draft","notes":""}}],"relations":[],"conflicts":[],"corrections":[],"research":null}