PHOSPHORYLATION OF DYNAMIN BY ERK2 INHIBITS THE DYNAMIN-MICROTUBULE INTERACTION

In the present study we show that purified bovine brain dynamin can be phosphorylated by MAP kinase, ERK2, with a stoichiometry of 1 mol pho sphate/mol dynamin. The phosphorylated serine residue is located withi n the C-terminal 10 kDa of dynamin. Dynamin I phosphorylated by ERK2 c an be specifically dephosphorylated by calcineurin but not by protein phosphatase 2A (PP2A). Phosphorylation of dynamin by ERK2 weakens the binding of dynamin to microtubules and inhibits dynamin's microtubule- activated GTPase activity, Stimulation of GTPase activity by either Gr b2 or phospholipids was not affected by ERK2 phosphorylation, suggesti ng that the binding sites for Grb2 and phospholipids do not overlap dt h that for microtubules.