Biosynthesis, glycosylation, and in vitro translation of the human T cell antigen Leu-4

Two families of polypeptides were found in immunoprecipitates formed from human T cell lines by using the monoclonal antibody anti-Leu-4. When analyzed by one-and two-dimensional SDS-PAGE, the first family consisted of members with m.w. of 26,000 and isoelectric points that varied from very basic to acidic. The second family consisted of members with m.w. of 22,000 to 23,000 and isoelectric points that varied from neutral to very acidic. The biosynthetic processing and intracellular glycosylation of several of these polypeptides were examined. Some, but not all, intracellular forms of the Leu-4 antigen contained N-linked oligosaccharides of the high mannose type. By using messenger RNA from human T cell lines, intracellular forms of Leu-4 were shown to be accurately translated and properly processed by Xenopus oocytes in vitro.