Studies on the Role of Glycosyltransferases in the Hepatic Binding of Asialoglycoproteins

Abstract

Abstract The presumed role of glycosyltransferases in the specific recognition and binding of asialoglycoproteins has been investigated utilizing a solubilized hepatic binding protein with a high specific activity for 125I-asialo-orosomucoid. Under optimally determined conditions, no transferase activity for sialic acid, galactose, N-acetylglucosamine, or fucose was detectable in the purified preparation. The inhibition of glycoprotein binding by α-lactalbumin, a specific modifier of galactosyltransferase, was confirmed and shown to result from competitive binding to the purified protein. In contrast to asialoglycoproteins, the binding of α-lactalbumin was independent of calcium and unaffected by EDTA.