DESCRIPTION: Myosin-VIIa is one of the unconventional members of the myosin molecular motor superfamily that move along filamentous actin. The protein is expressed primarily in the inner ear, retina and testis. Defects in the myosin-VIIa gene (MYO7A) are responsible for Usher syndrome, characterized by hearing impairment, lack of vestibular function and progressive retinal degeneration.MYO7A mutations are are responsible for deafness in shaker-1 mice and in other model systems. In the inner ear, myosin-VIIa is required for assembly of stereocilia, the sensory structures necessary for detecting sound signals.