ALTERED MOLECULAR-STRUCTURE OF HLA-DR ANTIGENS SYNTHESIZED IN THE PRESENCE OF TUNICAMYCIN

Effects of tunicamycin on the synthesis of proteins and glycoproteins, especially the surface antigens of a human lymphoblastoid cell line (Raji), were investigated. Electrophoretic profiles of [3H]leucine labeled membrane components were similar in the tunicamycin treated cells and untreated cells. However, the respective electrophoretic profiles of [3H]glucosamine labeled membrane components were remarkably different. In the presence of tunicamycin, the relative amount of HLA-DR antigens in the newly synthesized membrane was remarkably reduced, and both subunits of the antigens showed reduced apparent molecular weights. Moreover, one of the subunits completely lost its [3H]glucosamine labeled portion(s), and the other subunit still contained [3H]glucosamine labeled portion(s). These results imply that HLA-DR antigens possess either lipid carrier dependent oligosaccharides or other type(s) of oligosaccharide(s). © 1979 Academic Press, Inc. All rights of reproduction in any form reserved.