Dynamin is a GTPase stimulated to high levels of activity by microtubules

Abstract

DYNAMIN was initially identified in calf brain tissue as a protein of relative molecular mass 100,000 which induced nucleotide-sensitive bundling of microtubules¹. Purified dynamin showed only trace ATPase activity. But in combination with an activating factor removed during the purification, it exhibited microtubule-activated ATPase activity and dynamin-induced bundles showed evidence of ATP-dependent force production¹. Dynamin is the product of the Drosophila gene shibire^2,3, which has been implicated in synaptic vesicle recycling^4,5 and, more generally, in the budding of endocytic vesicles from the plasma membrane^6,7. Dynamin also shows⁸ extensive homology with proteins that participate in vacuolar protein sorting⁹ and spindle polebody separation¹⁰ in yeast, and in interferon-induced viral resistance^11,12 in mammals. All members of this family contain consensus sequence elements consistent with GTP binding near their amino termini, although none has been shown to have GTPase activity. We report here that dynamin is a specific GTPase which can be stimulated to very high levels of activity by microtubules.