title: Isolation and some properties of a new binding protein for asialoorosomucoid from rat liver.
abstract: Binding proteins for asialoorosomucoid were prepared from rat liver previously labeled in vivo with [3H]leucine by affinity chromatography on asialoorosomucoid-Sepharose 4B. They were subjected again to the same affinity chromatography and eluted into two fractions successively with 10 mM Tris-HCl buffer, pH 7.8, containing 1.25 M NaCl, 1% Triton X-100 and 50 mM lactose and 20 mM ammonium acetate buffer, pH 6.0, containing 1.25 M NaCl and 1% Triton X-100, and designated as ABP-I and ABP-II (asialoorosomucoid binding proteins), respectively. ABP-I corresponds to the receptor protein specific for asialoglycoproteins which has been extensively investigated by Ashwell and collaborators (J. Biol. Chem. 254, 1038-1043, 1979). ABP-II is different from ABP-I in several properties such as molecular weight, antigenicity and solubility. The molecular weight of ABP-II was estimated to be 29,000 by SDS-PAGE. On gel filtration it behaved as a pentamer with an apparent molecular weight of 150,000. Unlike ABP-I, ABP-II showed no detectable binding activity when assayed according to the procedures of Hudgin et al. (J. Biol. Chem. 249, 5536-5543, 1974). The calcium ion was, however, essential for the binding of ABP-II to asialoorosomucoid-Sepharose 4B similar to ABP-I. ABP-II can be extracted from the total microsomes of rat liver in 1.0 M NaCl by sonication after freezing and thawing. This suggests that ABP-II is either a soluble protein or a peripheral membrane protein loosely attached to the intracisternal cavities of the microsomal membranes.
mesh_terms: D000818:Animals; D037263:Asialoglycoprotein Receptor; D001212:Asialoglycoproteins; D055598:Chemical Phenomena; D002621:Chemistry; D007074:Immunoglobulin G / Q000276:immunology; D066298:In Vitro Techniques; D008099:Liver / Q000378:metabolism*; D008297:Male; D008862:Microsomes, Liver / Q000378:metabolism; D008970:Molecular Weight; D009961:Orosomucoid / Q000031:analogs & derivatives* / Q000378:metabolism; D011485:Protein Binding; D051381:Rats; D011919:Rats, Inbred Strains; D011956:Receptors, Cell Surface / Q000302:isolation & purification*; D012995:Solubility
chemical_list: D037263:Asialoglycoprotein Receptor; D001212:Asialoglycoproteins; D007074:Immunoglobulin G; D009961:Orosomucoid; D011956:Receptors, Cell Surface; C017030:asialoorosomucoid