Regulation of dynamin I GTPase activity by G protein beta gamma subunits and phosphatidylinositol 4,5-bisphosphate

Dynamin I is a 100-kDa GTPase that plays an important role in the recycling of synaptic vesicles. Hydrolysis of GTP by dynamin is thought to be a critical step in fission of coated pits to form coated vesicles. We report that the heterotrimeric G protein beta gamma subunit complex (G(beta gamma)) and phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P-2) are negative and positive regulators of dynamin GTPase activity, respectively. Furthermore, the apparent affinity of dynamin for G(beta gamma) is substantially enhanced by PtdIns(4,5)P-2. However, the GTPase activity of oligomeric dynamin is unaffected by G(beta gamma). The effects of heterotrimeric G proteins on endocytosis may thus be mediated directly and not involve more remote aspects of their signaling properties.