Low concentration of reserpine accelerates actin polymerization via interaction with G-actin

S Nakamura, K Ohmi and Y Nonomura

Department of Pharmacology, Faculty of Medicine, University of Tokyo, Japan.

The effect of reserpine on actin polymerization was examined by measurement of the changes in high shear viscosity and by electron microscopic observation of the actin solution. In the presence of low concentrations of reserpine, the time course of actin polymerization was accelerated dose dependently (up to approximately 0.5 nM), without affecting the final level of viscosity. The effect of reserpine rather decreased with dosages over this concentration. The binding of reserpine to actin was tested by developing the mixture of G- or F- actin and [3H]reserpine through a Sephadex G-50 column. A portion of the reserpine coeluted with G-actin, but little reserpine did with F- actin. This means that reserpine bound to G-actin but scarcely to F- actin. The binding of reserpine to G-actin was also confirmed using the method of photoaffinity labeling. After the irradiation of the mixed G- actin and [3H]reserpine by ultraviolet light, they were subjected to SDS-PAGE followed by fluorography. It was demonstrated that reserpine was bound to G-actin covalently by the ultraviolet light irradiation. This indicated the close interaction of reserpine with G-actin. Thus, the effect of reserpine on actin polymerization seemed to be exerted via interaction with G-actin.

Volume 33, Issue 6, pp. 604-610, 06/01/1988
Copyright © 1988 by American Society for Pharmacology and Experimental Therapeutics