| Abstract: | Lectin-resistant mutants with specific defects in glycosylation have been selected from the mouse lymphoma cell line, BW5147 (Thy-1+). The quantitative expression of cell surface glycoproteins on the mutant cells has been studied. The results show that some glycosylation defects that confer resistance to the cytotoxic effects of concanavalin A block the expression of Thy-1 glycoprotein on the cell surface. However, some changes in the oligosaccharides of Thy-1 glycoprotein generated by glycosylation defects found in PHAR mutant cells and restricted to the termini of complex-type oligosaccharides have no effect on the ability of Thy-1 to reach the cell surface. No glycosylation defects were found that interfered with the expression of either gp 69,71 or H-2 on the surface of the mutant cells. It is concluded that aberrant biosynthesis of Thy-1 oligosaccharides can interfere with its expression on the cell surface, but that specific changes in oligosaccharide structure are necessary to block transport to the cell surface and integration into the plasma membrane. |
