FIG. 2.

Correlation between Nef-induced CD4 down-regulation and endocytosis. (A) Internalization of CD4 in response to coexpression of wild-type or mutant Nef in 293T cells. CD4 was expressed alone or together with wild-type Nef or various Nef mutants as noted on the graphs. The results are representative of two independent experiments. Only the Nef mutants which down-modulate CD4 surface levels trigger its accelerated endocytosis in trans. (B) Diagram of interactions measured in this trans-endocytosis assay. Myristoylated Nef associates with the cytoplasmic tail of CD4 and also with the cell surface AP-2, a component of CCP.