Chromaffin cell scinderin, a novel calcium dependent actin severing protein.

Abstract

The study describes the purification and characterization of a novel Ca$\sp{2+}$ activated actin severing protein, scinderin present in the chromaffin cell of the adrenal medulla. Scinderin has been purified to homogeneity using a combination of chromatographic procedures. The protein has an apparent molecular weight of 79,600 $\pm$ 450 daltons, three isoforms and two calcium binding sites; a high affinity site, and a low affinity site. Scinderin interacts with F-actin in the presence of Ca$\sp{2+}$ and produces a decrease in the viscosity of actin gels as a result of F-actin filament severing as demonstrated by electron microscopy. Scinderin is a structurally and immunologically different protein from chromaffin cell gelsolin. This protein is mainly located in the subplasmalemma region of the chromaffin cell. Presence of scinderin and gelsolin, two Ca$\sp{2+}$ dependent actin severing proteins in the same cell suggests the possibility of synergistic functions by the two proteins in the control of cellular actin filament networks. Alternatively, the actin severing activity of the two proteins might be under the control of different transduction and modulating influences. (Abstract shortened by UMI.)