Otoconin-90 (OC90) is a major protein of the otoconia, a calcium carbonate structure in the saccule and utricle of the ear that is essential for perception of gravity and maintenance of balance [, ]. OC90 contains two globular domains homologous to secretory phospholipase A2 (PLA2) connected by a linker segment. The PLA2-like domains in otoconins may have lost their metal-binding sites [].
