We study the role of proteins that form and maintain stereocilia to better understand their place in bundle’s integrity and maintenance. Several such proteins, critical for stereocilia function, form the hair cell mechanotransduction complex, which converts sound to an electrical signal our brain can understand. Malfunction of many of these proteins causes Usher syndrome, a devastating disease that affects both hearing and vision. We use state-of-the-art electrophysiology, optical microscopy, and electron microscopy techniques to better understand the function of the individual proteins within the complex and to develop new gene therapy methods to treat Usher syndrome in both the ear and eye.