title: Solubilization and preliminary characterization of the human ileal vitamin B12-intrinsic factor receptor.
abstract: The human ileal intrinsic factor receptor was solubilized with Triton X-100 using an improved method originally devised for the porcine receptor. At pH 7.4 and in the presence of Ca2+ the receptor bound the vitamin B12 complexes of normal human and pig intrinsic factor but not that of an abnormal biologically inert human intrinsic factor. EGTA dissociated vitamin B12-intrinsic factor from the receptor complexes. The solubilized vitamin B12-intrinsic factor receptor complex consisted of three to four molecular species termed HC-L, HC-20 S, HC-12 S and HC-8.5 S (the three last-mentioned referring to sedimentation coefficients). Of these HC-20 S was the dominating component and had a Stokes radius of 18 nm. Radioactive calcium was shown to be bound to vitamin B12-intrinsic factor and to be contained in its complex with the receptor.
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D003037:Cobalt Radioisotopes; D005750:Gastric Juice; D006801:Humans; D007082:Ileum / Q000032:analysis*; D007413:Intestinal Mucosa / Q000032:analysis*; D007437:Intrinsic Factor / Q000378:metabolism*; D011955:Receptors, Drug / Q000302:isolation & purification* / Q000378:metabolism; D012995:Solubility; D013552:Swine; D014805:Vitamin B 12 / Q000378:metabolism; D008258:Waldenstrom Macroglobulinemia / Q000378:metabolism
chemical_list: D003037:Cobalt Radioisotopes; D011955:Receptors, Drug; D007437:Intrinsic Factor; D014805:Vitamin B 12; D002118:Calcium