Acts as a GTPase-activating protein (GAP) for ARL2 with low specific activity. Also present in the cuticular plate of auditory hair cells. In the organ of Corti, in inner hair cells, expressed along the length of the stereocilia, but excluded from the very tip. Colocalizes with F-actin cytoskeleton. Both isoform 1 and isoform 2 are widely expressed. Both isoform 1 and isoform 2 are expressed postnatally in the inner ear. Expression increases from P0 to P30 in both cochlear and vestibular tissues; at all time points, isoform 2 is expressed at several-fold higher levels than isoform 1. At P14, in the organ of Corti, detected along the length of stereocilia of hair cells, particularly in the upper half. Also observed in the microvilli on the apical surface of the hair cells. More abundant in the stereocilia of inner hair cells than in those of outer hair cells (at protein level). In the vestibular sensory epithelium, localizes within the hair cell and supporting cell bodies in the saccule and utricule. Not detected in vestibular hair bundles (at protein level).