Interaction of mastoparan with the low molecular mass GTP‐binding proteins rho/rac

Abstract
Mastoparan, which has been shown to active G proteins [1], inhibits the ADP‐ribosylation of 20 kDa human platelet membrane proteins catalyzed by Clostridium botulinum exoenzyme C3 half‐maximally and maximally (90%) at 20 and 100 μM concentrations, respectively. Inhibition of ADP‐ribosylation was enhanced by GTP‐γS. Mastoparan increased GTP hydrolysis by porcine brain rho protein and stimulated GTP binding in a concentration dependent manner. The data suggest that mastoparan not only interacts with heterotrimeric G proteins but also with low molecular mass GTP‐binding proteins of the rho/rac family.