Isolation of a biotin receptor from hepatic plasma membranes

Biotin, one of the growth promoting members of the B complex vitamin family, was found in the present investigation to have a specific receptor on isolated plasma membranes. Biotin bound to its receptor in a linear manner at 20 degrees C with some binding as early as 30 minutes and full equilibrium binding being present at 20 hours. The best binding was found at 0.6 mg/ml of protein, but significant binding was still present at 0.6 microgram/ml. The saturation of ligand binding sites was at 10(-7)M. Half maximal saturation of binding was between 10(-9) and 10(-10)M. These results demonstrate that a receptor for biotin does exist on purified plasma membranes.