May play a role in stabilizing dense microtubular networks or in vesicular trafficking. Preferentially expressed in the inner ear and testis. Localizes mainly in the kinocilium of sensory cells in the inner ear. Also present in the manchette of the spermatids, a transient structure enriched in interconnected microtubules (at protein level). First detected in the kinocilia of vestibular and auditory hair cells at embryonic days 14.5, and 18.5, respectively. In the mature vestibular hair cells, it is still present in the kinocilium. As the auditory hair cells begin to lose the kinocilium during postnatal development, it becomes distributed in an annular pattern at the apex of these cells, where it colocalizes with the tubulin belt. In mature auditory hair cells, it is also present at the level of the cuticular plate, at the base of each stereocilium. As the kinocilium regresses from developing auditory hair cells, it begins to be expressed by the pillar cells and Deiters cells, that both contain prominent transcellular and apical bundles of microtubules. Not detected in the supporting cells in the vestibular end organs (at protein level).