Noninvolvement of a rat intestinal folate binding protein in physiological folate absorption.
Folic acid and its derivatives are observed to be instantaneously bound to rat intestinal mucosal cell curface binding protein. Various parameters were measured such as the optimal pH for binding (6.5), the saturation kinetics observed for folate binding and the avid affinity with which polyglutamyl folates are preferentially bound to the binder. A comparison of the observed results with the conditions reported as favorable for intestinal folate absorption in the rat precludes the involvement of this folate-binding protein in the physiological absorption of folates.
D000818:Animals; D001667:Binding, Competitive; D002352:Carrier Proteins / Q000502:physiology*; D058973:Folate Receptors, GPI-Anchored; D005492:Folic Acid / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007408:Intestinal Absorption; D007413:Intestinal Mucosa / Q000378:metabolism; D007421:Intestine, Small / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D011956:Receptors, Cell Surface
D002352:Carrier Proteins; D058973:Folate Receptors, GPI-Anchored; D011956:Receptors, Cell Surface; D005492:Folic Acid