Abnormal lipid-linked oligosaccharides in class E Thy-1-negative mutant lymphomas.

The glycosylation defect of Thy-1-mutant lymphomas of the class E complementation group has been identified as a block in the synthesis of the lipid-linked oligosaccharide precursor of the asparagine-linked oligosaccharides of glycoproteins. Two major lipid-linked oligosaccharides were isolated from the mutant cells. Both oligosaccharides were smaller than the lipid-linkid oligosaccharides of wild-type lymphomas and, in contrast to the lipid-linked oligosaccharides isolated from wild-type cells, both were resistant to digestion with endoglycosidase H. The oligosaccharides of newly synthesized polypeptides in class E Thy-1-cells were also resistant to endoglycosidase H digestion, providing strong evidence that they are derived from the abnormal lipid-linked oligosaccharides.