{"id":"8c82c0ca-ba48-539b-95a9-2a65ea031b9e","stable_key":"cb568d28-484a-5c2e-9fcc-2d780358e514:vc-transport-rbc-sugar-competition","predicate":"competes-with","statement":"Human erythrocyte and inside-out-vesicle kinetic assays showed DHA and 3-O-methylglucose competing at both membrane faces, consistent with transport through the same GLUT1 complex.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"context_dependent","is_public":true,"mechanism_event_id":"dcee90c4-15ab-5e46-a0af-309be4c4db8c","mechanism_event_label":"A later kinetic study found that sugar and oxidized vitamin C share the red-cell GLUT1 transport pathway.","subject":{"id":"f06aba9f-6e67-5b24-814b-d04342ab1b0c","slug":"3-o-methyl-d-glucose","display_name":"3-O-Methyl-D-glucose","entity_type_key":"small_molecule"},"object":{"id":"e6658c2b-ccff-5122-80a5-2e153f12ba90","slug":"dehydroascorbic-acid","display_name":"Dehydroascorbic acid","entity_type_key":"small_molecule"},"evidence_count":1,"mechanism_event":{"id":"dcee90c4-15ab-5e46-a0af-309be4c4db8c","stable_key":"cb568d28-484a-5c2e-9fcc-2d780358e514:vc-transport-rbc-sugar-competition-event","event_type":"biochemical_relationship","label":"A later kinetic study found that sugar and oxidized vitamin C share the red-cell GLUT1 transport pathway.","description":"Human erythrocyte and inside-out-vesicle kinetic assays showed DHA and 3-O-methylglucose competing at both membrane faces, consistent with transport through the same GLUT1 complex.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"ffb5e632-9a8e-5bed-97eb-56a9ecdd856f","slug":"slc2a1","display_name":"Human glucose transporter 1 / SLC2A1","entity_type_key":"protein"},"role":"shared transporter","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"f06aba9f-6e67-5b24-814b-d04342ab1b0c","slug":"3-o-methyl-d-glucose","display_name":"3-O-Methyl-D-glucose","entity_type_key":"small_molecule"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"e6658c2b-ccff-5122-80a5-2e153f12ba90","slug":"dehydroascorbic-acid","display_name":"Dehydroascorbic acid","entity_type_key":"small_molecule"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""}]},"contexts":[{"dimension":"cross_nutrient","value_text":"true","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Human erythrocytes, ghosts and inside-out membrane vesicles","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"Initial-rate substrate competition and trans-acceleration assays","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"3-O-methylglucose is a transport probe, not dietary glucose. This challenges segregated transport pools without denying vitamin C recycling.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Vitamin C research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"vitamin-c","display_name":"Vitamin C","entity_type_key":"chemical_species"}},{"dimension":"organism","value_text":"Homo sapiens","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"A later kinetic study found that sugar and oxidized vitamin C share the red-cell GLUT1 transport pathway.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[sage2014] Human erythrocytes transport dehydroascorbic acid and sugars using the same transporter complex. (2014). https://pubmed.ncbi.nlm.nih.gov/24598365/ DOI: 10.1152/ajpcell.00044.2014","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Erythrocyte plasma membrane and inside-out vesicles","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"83a07d5f-51f8-5b5d-b07e-940efd77ba6e","evidence_kind":"source_excerpt","locator":"Lines 533-544","start_line":533,"end_line":544,"excerpt":"### vc-transport-rbc-sugar-competition\nHuman erythrocyte and inside-out-vesicle kinetic assays showed DHA and 3-O-methylglucose competing at both membrane faces, consistent with transport through the same GLUT1 complex.\nCondition category: normal\nnutrient_topic: Vitamin C research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: A later kinetic study found that sugar and oxidized vitamin C share the red-cell GLUT1 transport pathway.\norganism: Homo sapiens\ntissue_or_cell_type: Erythrocyte plasma membrane and inside-out vesicles\nexperimental_model: Human erythrocytes, ghosts and inside-out membrane vesicles\nlimitations: 3-O-methylglucose is a transport probe, not dietary glucose. This challenges segregated transport pools without denying vitamin C recycling.\nexposure: Initial-rate substrate competition and trans-acceleration assays\ncross_nutrient: true\n[sage2014] Human erythrocytes transport dehydroascorbic acid and sugars using the same transporter complex. (2014). https://pubmed.ncbi.nlm.nih.gov/24598365/ DOI: 10.1152/ajpcell.00044.2014","model_system":"Human erythrocytes, ghosts and inside-out membrane vesicles","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [sage2014] Human erythrocytes transport dehydroascorbic acid and sugars using the same transporter complex. (2014). https://pubmed.ncbi.nlm.nih.gov/24598365/ DOI: 10.1152/ajpcell.00044.2014","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"fa811221-13bd-5c10-adc1-eaf097c7703c","stable_key":"import-cb568d28-484a-5c2e-9fcc-2d780358e514","title":"Vitamin C: 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":"b7fd83f956abb81855f2ea23199ba14e465cd91f4a2ac560277ec21ddafd7bfc","revision_id":"6cde9bbb-d712-5746-82a6-85b144253efa","review_status":"unverified_draft","notes":""}}],"relations":[],"conflicts":[{"id":"e21e2978-d8fe-5a70-9aa4-3bcb19306115","title":"Does mature erythrocyte GLUT1 preferentially transport DHA through a segregated pool?","kind":"contradiction","status":"open","why":"The 2008 study interpreted glucose-insensitive DHA accumulation as a stomatin-regulated substrate switch. The 2014 primary kinetic study explicitly argues against that model and finds shared sugar/DHA transport and competition.","resolution":"Keep both findings with assay conditions. Favor initial transport kinetics for claims about competition; do not translate the 2008 interpretation into universal glucose-insensitive transport or the 2014 result into dietary carbohydrate harm.","created_at":"2026-09-17 12:19:14","record_type":"conflict","display_label":"Recorded conflict","record_url":"/conflicts/e21e2978-d8fe-5a70-9aa4-3bcb19306115","sides":[{"conflict_id":"e21e2978-d8fe-5a70-9aa4-3bcb19306115","ordinal":0,"label":"2008: glucose-insensitive DHA accumulation and preferential-transport interpretation","revision_id":"6cde9bbb-d712-5746-82a6-85b144253efa","start_line":520,"end_line":531,"quote":"### vc-transport-rbc-glucose-noncompetition\nMontel-Hagen et al. reported that 5 mM glucose did not inhibit DHA accumulation in mature human erythrocytes and interpreted this as preferential DHA transport.\nCondition category: normal\nnutrient_topic: Vitamin C research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: One study reported that glucose did not compete with oxidized vitamin C uptake in mature red cells.\norganism: Homo sapiens\ntissue_or_cell_type: Mature erythrocytes\nexperimental_model: Human erythroid progenitors, mature RBCs and A431 stomatin transfection\nlimitations: Published interpretation challenged by kinetic analyses that distinguish transport, intracellular reduction and sugar loading.\nexposure: 5 mM glucose with radiolabeled DHA; room-temperature uptake time courses\ncross_nutrient: true\n[montelhagen2008] Erythrocyte Glut1 triggers dehydroascorbic acid uptake in mammals unable to synthesize vitamin C. (2008). https://pubmed.ncbi.nlm.nih.gov/18358815/ DOI: 10.1016/j.cell.2008.01.042","source_key":"import-cb568d28-484a-5c2e-9fcc-2d780358e514","source_title":"Vitamin C: mechanisms, deficiency and nutrient interactions (2026-09-17)","claim_ids":["8da0949a-0ae2-5ee1-a9cf-774c9de8ae6b"]},{"conflict_id":"e21e2978-d8fe-5a70-9aa4-3bcb19306115","ordinal":1,"label":"2014: shared transport complex and competition in kinetic assays","revision_id":"6cde9bbb-d712-5746-82a6-85b144253efa","start_line":533,"end_line":544,"quote":"### vc-transport-rbc-sugar-competition\nHuman erythrocyte and inside-out-vesicle kinetic assays showed DHA and 3-O-methylglucose competing at both membrane faces, consistent with transport through the same GLUT1 complex.\nCondition category: normal\nnutrient_topic: Vitamin C research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: A later kinetic study found that sugar and oxidized vitamin C share the red-cell GLUT1 transport pathway.\norganism: Homo sapiens\ntissue_or_cell_type: Erythrocyte plasma membrane and inside-out vesicles\nexperimental_model: Human erythrocytes, ghosts and inside-out membrane vesicles\nlimitations: 3-O-methylglucose is a transport probe, not dietary glucose. This challenges segregated transport pools without denying vitamin C recycling.\nexposure: Initial-rate substrate competition and trans-acceleration assays\ncross_nutrient: true\n[sage2014] Human erythrocytes transport dehydroascorbic acid and sugars using the same transporter complex. (2014). https://pubmed.ncbi.nlm.nih.gov/24598365/ DOI: 10.1152/ajpcell.00044.2014","source_key":"import-cb568d28-484a-5c2e-9fcc-2d780358e514","source_title":"Vitamin C: mechanisms, deficiency and nutrient interactions (2026-09-17)","claim_ids":["8c82c0ca-ba48-539b-95a9-2a65ea031b9e"]}]}],"corrections":[],"research":null}