Required for proper hearing, plays a role in maintaining the integrity of the tectorial membrane. Homooligomer; can for homodimers and homotetramers (By similarity). Interacts with TECTA and TECTB (PubMed:25080593). Localizes at the tip of cochlear outer hair cells and to the tectorial membrane. Expressed in cochlear outer hair cells (OHC). Abundantly expressed in cochleae from embryonic day 17 to postnatal day 42. Mutant mice show loss of striated-sheet matrix and Hensen's stripe, a prominent feature in the basal two-thirds of the tectorial membrane. They have enhanced spontaneous, stimulus-frequency, and transiently evoked otoacoustic emissions. Belongs to the immunoglobulin superfamily. CEA family.