Confirmation of the arginine-finger hypothesis for the GAP-stimulated GTP-hydrolysis reaction of Ras.

RasGAPs supply a catalytic residue, termed the arginine finger,into the active site of Ras thereby stabilizing the transition state of the GTPase reaction and increasing the reaction rate by more than one thousand-fold, in good agreement with the structure of the Ras.RasGAP complex.