Subcellular distribution of a mammalian hepatic binding protein specific for asialoglycoproteins

Abstract

Evidence is presented to support the identification of a unique membrane binding protein in a variety of subcellular organelles including the Golgi complex, the lysosomes, the smooth microsomes, and the external plasma membranes prepared from rat liver homogenates. The binding protein, specific for desialylated serum glycoproteins, was isolated from each of the above components and purified by affinity chromatography on a column of Sepharose 4B to which asialoorosomucoid had been covalently linked. In each case, the final preparation exhibited an apparently complete identity of binding properties as well as similar subunit structure and immunological specificity. In contrast to the binding role previously ascribed to the plasma membranes as a prelude to transport and catabolism, the function of this activity in intracellular processes is currently unknown.