Chromaffin granule-cytoskeleton interaction. Stabilization by F-actin of ATPase in purified chromaffin granule membranes

The influence of cytoskeletal elements on the chromaffm granule function was studied using a model system consisting of purified granule membranes and F-actin. The membrane ATPase was partially inactivated by incubation at 37 °C, and this inactivation was prevented by adding F-actin. The stabilizing action of F-actin on the ATPase was abolished by adding DNase I. Detergent-solubilized ATPase was more rapidly and profoundly inactivated, but was not stabilized by F-actin. The stabilization of ATPase by F-actin may be due to the cross-linking of granule membranes with F-actin and the native structure of the granule membrane may be required for preserving the stability of membrane ATPase. These findings thus suggest the possibility that the interaction of microfilaments with chromaffin granules may influence the function of chromaffin granules within the cell.