{"id":"8888252e-ea71-574c-bd01-a890c95131ec","stable_key":"548ab9d6-3a9b-5bed-879c-17d03813b636:transport-slc52a2-w31s-intrinsic-defect","predicate":"reduces","statement":"RFVT2 W31S abolished measurable uptake despite detectable membrane expression in the study, separating transport failure from simple protein absence.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"negative","is_public":true,"mechanism_event_id":"38e42c84-1d24-5bf1-bb5c-c2ccf9d9663c","mechanism_event_label":"A transporter can reach the membrane yet fail to carry riboflavin.","subject":{"id":"e0a50db2-2a25-566a-821f-ad37a4b27c95","slug":"slc52a2-w31s","display_name":"SLC52A2 W31S variant","entity_type_key":"protein_state"},"object":{"id":"4d513cb9-67ef-53b3-bf96-b35813191439","slug":"cellular-riboflavin-uptake","display_name":"Cellular riboflavin uptake","entity_type_key":"cellular_process"},"evidence_count":1,"mechanism_event":{"id":"38e42c84-1d24-5bf1-bb5c-c2ccf9d9663c","stable_key":"548ab9d6-3a9b-5bed-879c-17d03813b636:transport-slc52a2-w31s-intrinsic-defect-event","event_type":"biochemical_relationship","label":"A transporter can reach the membrane yet fail to carry riboflavin.","description":"RFVT2 W31S abolished measurable uptake despite detectable membrane expression in the study, separating transport failure from simple protein absence.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"e0a50db2-2a25-566a-821f-ad37a4b27c95","slug":"slc52a2-w31s","display_name":"SLC52A2 W31S variant","entity_type_key":"protein_state"},"role":"variant-transporter","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"86eb1eee-a8d1-539c-8c17-0911f69b6f1b","slug":"riboflavin","display_name":"Riboflavin (vitamin B2)","entity_type_key":"small_molecule"},"role":"substrate","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"4d513cb9-67ef-53b3-bf96-b35813191439","slug":"cellular-riboflavin-uptake","display_name":"Cellular riboflavin uptake","entity_type_key":"cellular_process"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""}]},"contexts":[{"dimension":"availability_state","value_text":"machinery_impairment","comparator":null,"unit":null,"notes":"Imported condition classification; unverified.","entity":null},{"dimension":"evidence_location","value_text":"Figure 5A-B","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"HEK293 transient expression, tracer uptake and membrane immunoblot","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"W31S expression compared with wild type.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Crude-membrane detection does not quantify correctly oriented surface protein.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Riboflavin research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"riboflavin","display_name":"Riboflavin (vitamin B2)","entity_type_key":"small_molecule"}},{"dimension":"organism","value_text":"Homo sapiens","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"A transporter can reach the membrane yet fail to carry riboflavin.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[transport-slc52a2-neuronopathy-2014] Treatable childhood neuronopathy caused by mutations in riboflavin transporter RFVT2 (2014). https://pmc.ncbi.nlm.nih.gov/articles/PMC3891447/ DOI: 10.1093/brain/awt315","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"HEK293 cells","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"trigger_kind","value_text":"machinery_impairment","comparator":null,"unit":null,"notes":"Imported condition classification; unverified.","entity":null}],"evidence":[{"id":"03213316-8a3a-55fe-a374-2934b247cf19","evidence_kind":"source_excerpt","locator":"Lines 464-475","start_line":464,"end_line":475,"excerpt":"### transport-slc52a2-w31s-intrinsic-defect\nRFVT2 W31S abolished measurable uptake despite detectable membrane expression in the study, separating transport failure from simple protein absence.\nCondition category: machinery_impairment\nnutrient_topic: Riboflavin research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: A transporter can reach the membrane yet fail to carry riboflavin.\norganism: Homo sapiens\ntissue_or_cell_type: HEK293 cells\nexperimental_model: HEK293 transient expression, tracer uptake and membrane immunoblot\nlimitations: Crude-membrane detection does not quantify correctly oriented surface protein.\nexposure: W31S expression compared with wild type.\nevidence_location: Figure 5A-B\n[transport-slc52a2-neuronopathy-2014] Treatable childhood neuronopathy caused by mutations in riboflavin transporter RFVT2 (2014). https://pmc.ncbi.nlm.nih.gov/articles/PMC3891447/ DOI: 10.1093/brain/awt315","model_system":"HEK293 transient expression, tracer uptake and membrane immunoblot","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [transport-slc52a2-neuronopathy-2014] Treatable childhood neuronopathy caused by mutations in riboflavin transporter RFVT2 (2014). https://pmc.ncbi.nlm.nih.gov/articles/PMC3891447/ DOI: 10.1093/brain/awt315","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"4f7c9578-82bf-5e2d-b5c4-72a79fb4f6af","stable_key":"import-548ab9d6-3a9b-5bed-879c-17d03813b636","title":"Riboflavin: 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":"680cb6bc8249877f2410f551807f10d390fdd719014137d7414ba3420e29228d","revision_id":"7a61e299-908d-5372-860b-99ed190f9d7a","review_status":"unverified_draft","notes":""}}],"relations":[],"conflicts":[],"corrections":[],"research":null}