Influence of the N-linked oligosaccharides on the biosynthesis, intracellular routing, and function of the human asialoglycoprotein receptor.
The human asialoglycoprotein receptor (ASGP-R) is a membrane glycoprotein of 46,000 Da which possesses two N-linked oligosaccharide chains (Schwartz, A. L., and Rup, D. (1983) J. Biol. Chem. 258, 11249-11255). In order to examine the role of N-linked oligosaccharides in the biosynthesis, intracellular routing, and function of the ASGP-R, we have used Hep G2 cells, which have a large number of ASGP-R, and two inhibitors of glycosylation, swainsonine and tunicamycin. In the presence of swainsonine, newly synthesized ASGP-R is a 43,000-Da species which is endoglycosidase H-sensitive, appears on the Hep G2 cell surface, and specifically binds 125I-asialoorosomucoid (ASOR). In the presence of tunicamycin newly synthesized ASGP-R is a 34,000-Da nonglycosylated species which appears on the Hep G2 cell surface where it specifically binds 125I-ASOR. There is no major effect on subsequent uptake and degradation of 125I-ASOR in cells whose ASGP-R was synthesized in the presence of tunicamycin. The turnover of ASGP-R synthesized in the presence of either swainsonine or tunicamycin is not significantly altered from that found for the normal 46,000-Da species. Thus, it appears that the two N-linked oligosaccharide chains of the human ASGP-R do not play a major role in the intracellular routing, turnover, or function of ASGP-R.
D000470:Alkaloids / Q000494:pharmacology; D037263:Asialoglycoprotein Receptor; D006528:Carcinoma, Hepatocellular; D002460:Cell Line; D006801:Humans; D007700:Kinetics; D008113:Liver Neoplasms; D009844:Oligosaccharides / Q000502:physiology*; D009961:Orosomucoid / Q000031:analogs & derivatives / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000187:drug effects / Q000302:isolation & purification / Q000378:metabolism*; D017026:Swainsonine; D014415:Tunicamycin / Q000494:pharmacology
D000470:Alkaloids; D037263:Asialoglycoprotein Receptor; D009844:Oligosaccharides; D009961:Orosomucoid; D011956:Receptors, Cell Surface; D014415:Tunicamycin; D017026:Swainsonine