DYNAMIN UNDERGOES A GTP-DEPENDENT CONFORMATIONAL CHANGE CAUSING VESICULATION

The dynamin family of GTPases is essential for receptor-mediated endoc ytosis and synaptic vesicle recycling, and it has recently been shown to play a role in vesicle formation from the trans-Golgi network. Dyna min is believed to assemble around the necks of clathrin-coated pits a nd assist in pinching vesicles from the plasma membrane. This role wou ld make dynamin unique among GTPases in its ability to act as a mechan ochemical enzyme. Data presented here demonstrate that purified recomb inant dynamin binds to a lipid bilayer in a regular pattern to form he lical tubes that constrict and vesiculate upon GTP addition. This sugg ests that dynamin alone is sufficient for the formation of constricted necks of coated pits and supports the hypothesis that dynamin is the force-generating molecule responsible for membrane fission.