The cytochalasins are cell-permeable fungal metabolites which inhibit actin polymerization. This interferes with such diverse processes as cell movement, growth, phagocytosis, degranulation, and secretion. Cytochalasin A is an oxidized analog of cytochalasin B which uniquely inhibits HIV-1 protease (IC50 = 3 μM). Cytochalasins A and B differ from other cytochalasins in being able to rapidly and reversibly inhibit glucose transport by competitively binding glucose transporters (Ki = 4.0 and 0.6 μM, respectively). Cytochalasin A also induces the phosphorylation of the tyrosine phosphatase PTP3 of Dictyostelium, activating STATc.
