Villin can cap, nucleate, sever and bundle actin in a Ca2+ and phosphoinositide-regulated manner. It is associated with the microvillar actin core bundle of intestinal and renal brush border implicated in adsorption. Villin is composed of six repeats, each containing 150 residues that together constitute the core domain followed by the carboxylterminal headpiece domain of 87 residues. The core domain retains the Ca2+ dependent capping nucleating and severing activity, whereas the headpiece domain contributes towards actin filament bundling and binding F-actin, independently of Ca2+.