Studies on the effects of dansylcadaverine and related compounds on receptor-mediated endocytosis in cultured cells.

It has been suggested that cellular transglutaminases may play an important role in the process of receptor-mediated endocytosis. We have examined this premise by investigating the receptor-mediated endocytosis of two proteins, epidermal growth factor and alpha 2 macroglobulin in cells that are deficient in transglutaminases. We find that endocytic activity is normal in these cells, ruling out an obligatory role for transglutaminases in endocytosis. We do find, however, that dansylcadaverine is not an inhibitor of endocytosis in cells that lack transglutaminase activity. Immunofluorescent localization of dansylcadaverine in dansylcadaverine-treated cells demonstrates incorporation of the amino into endocytic vesicles. We believe that covalent coupling of dansylcadaverine to cellular membranes may account for its ability to interfere with endocytosis in certain susceptible cells.