Concanavalin A augments the turnover of electrophoretically defined thymocyte plasma membrane proteins

Abstract

1. 1. Rabbit thymocytes were labelled in vitro with 14C-labeled amino acids either before or during stimulation with concanavalin A. 2. 2. Plasma membranes were isolated from control and stimulated thymocytes and their proteins fractionated by sodium dodecylsulfate-polyacylamide gel electrophoresis. 3. 3. No qualitative and quantitative differences between the sodium dodecylsulfate-polyacrylamide gel electrophoresis patterns of membrane proteins from normal and concanavalin A-treated cells could be detected. 4. 4. Plasma membrane protein turnover is generally augmented by concanavalin A stimulation. 5. 5. The turnover of a sodium dodecylsulfate-polyacrylamide gel electrophoresis component with an apparent molecular weight of 55 000 is particularly enhanced. Moreover, concanavalin A induces excretion of this component into the cultivation medium. 6. 6. The data are discussed in terms of possible modes of interaction between concanavalin A and thymocyte plasma membranes.