Concanavalin A causes changes in membrane protein synthesis of human thymocytes

Human thymocytes maintained in culture for 32-51 h synthesize proteins de novo and incorporate [35S]methionine into specific membrane proteins. Radiolabelling patterns of membranes of thymocytes from different donors are comparable. Concanavalin A activation of human thymocytes in culture does not increase the rate of de novo protein synthesis of membrane proteins but causes specific changes in the pattern of synthesis of membrane proteins with time. After 32 h a radiolabelled band. MW 52 000, is apparent and after 51 h two additional radiolabelled bands MW 35 000 and MW 70 000 are detectable; concomitantly two proteins, MW 80 000 and 100 000 are no longer radiolabelled. These findings reflect changes in gene expression and suggest an acceleration in the normal processing of specific groups of membrane proteins.