Binding of intrinsic factor to ileal brush border membrane in the rat.
The rat ileal brush border membrane binds both free [125I]-intrinsic factor (IF) and the IF-[57Co]cobalamin (cbl) complex. This binding is observed with IF isolated from rat stomach, but not from IF isolated from hog, canine and human stomachs. The binding of rat-IF[57Co]cbl can be blocked with free rat IF but not with hog IF. The IF-cbl complex binds at a higher affinity (Ka = 0.15 X 10(9) M-1) compared to that of free IF (Ka = 0.9 X 10(9) M-1). Rat IF-cbl also binds efficiently to human and canine ileal membranes. While antibody to the canine ileal receptor blocks the binding of rat, human or hog IF-[57Co]cbl to human and canine ileal membranes, it does not affect the binding of rat IF-[57Co]cbl to rat ileal membranes. These findings demonstrate that the rat ileal receptor is different from canine and human ileal receptors.
D000818:Animals; D002462:Cell Membrane / Q000378:metabolism*; D004285:Dogs; D005750:Gastric Juice; D006801:Humans; D007082:Ileum / Q000378:metabolism*; D007413:Intestinal Mucosa / Q000378:metabolism*; D007437:Intrinsic Factor / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D008871:Microvilli / Q000378:metabolism*; D051381:Rats; D011956:Receptors, Cell Surface / Q000378:metabolism*; D013270:Stomach; D013552:Swine; D014805:Vitamin B 12 / Q000378:metabolism*
D011956:Receptors, Cell Surface; C029486:intrinsic factor-cobalamin receptor; D007437:Intrinsic Factor; D014805:Vitamin B 12