title: Protein-mediated uptake of vitamin B12 by isolated mitochondria.
abstract: Protein-mediated B12 uptake by isolated rat liver mitochondria has been shown to be enhanced by plasma transcobalamin (TC-II) but not by salivary R binder in vitro. The process is enhanced by calcium and depends on active mitochondrial respiration. Following uptake, cyanocobalamin is converted to adenosyl and methylcobalamins and released from the mitochondria. TC-II appears to be required for both cellular and mitochondrial uptake of vitamin B12.
mesh_terms: D000818:Animals; D002458:Cell Fractionation; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D008930:Mitochondria, Liver / Q000378:metabolism*; D011485:Protein Binding; D051381:Rats; D012463:Saliva / Q000378:metabolism; D014155:Transcobalamins / Q000378:metabolism; D014805:Vitamin B 12 / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D014155:Transcobalamins; D014805:Vitamin B 12