Calcium dependence of MYO3B motor function

Abstract

Class III myosins are actin based motors that localize to the tips of stereocilia in inner ear hair cells. In vertebrates, class III myosins exist in two isoforms, MYO3A and MYO3B. Mutations in MYO3A are associated with delayed-onset deafness, and MYO3B is proposed to partially compensate for the lack of functional MYO3A. Both MYO3A and MYO3B have been shown to bind espin, a stereocilia actin bundling protein, which may help facilitate elongation at the actin protrusion tips. In this study we discovered that MYO3B is regulated by micromolar concentrations of calcium, while MYO3A is not.