TY - JOUR T1 - Studies on the solubilized porcine ileal intrinsic factor receptor and on a 340 000-dalton component binding vitamin B-12. A1 - Marcoullis,G, PY - 1977/10/25/pubmed PY - 1977/10/25/medline PY - 1977/10/25/entrez SP - 373 EP - 81 JF - Biochimica et biophysica acta JO - Biochim Biophys Acta VL - 499 IS - 3 N2 - A 340 000-dalton component "C-III" was found when Triton X-100-containing extracts of ileal mucosa were incubated with human or porcine intrinsic factor vitamin B-12 preparations. It was not formed when abnormal human intrinsic factor, unable to attach to the intrinsic factor receptor, was used. Prolonged storage promoted the trnasfer of vitamin B-12 to it from the vitamin B-12-intrinsic factor recptor species C-I and C-II. The component was also present in ileal extracts prepared with or without detergent and it bound vitamin B-12 directly. Immunologically and by electrofocusing it could be classified as a cobalophilin but its molecular dimensions were larger than described for cobalophilin. It thus represents a novel vitamin B-12 binding protein, possibly a macromolecular acceptor of vitamin B-12 which accepts vitamin B-12 bound via intrinsic factor to the ileal intrinsic factor recptor. In the presence of EDTA or at low pH, vitamin B-12-intrinsic factor did not bind to any of the receptor species and under the same conditions it could all be dissociated from the receptor complexes but not from C-III. The dissociated receptor was able to recombine with vitamin B-12-intrinsic factor and it appeared to bind free and vitamin B-12-bound intrinsic factor in vivo. SN - 0006-3002 UR - https://www.unboundmedicine.com/medline/citation/911890/Studies_on_the_solubilized_porcine_ileal_intrinsic_factor_receptor_and_on_a_340_000_dalton_component_binding_vitamin_B_12_ L2 - https://linkinghub.elsevier.com/retrieve/pii/0304-4165(77)90068-X DB - PRIME DP - Unbound Medicine ER -