SPECIFIC PROTEINS OF THE ORGAN OF CORTI

The mammalian organ of Corti has achieved a degree of perfection unequ aled in other hair cell systems. Although cellular metabolism requires the coordinated action of thousands of proteins, the physical process es underlying auditory transduction in the OC are undoubtedly mediated by a much smaller subset of these. OCP1, OCP2, and CBP-15-identified by 2D-PAGE-are apparently members of this elite class. OCP1 and OCP2 a re restricted to the supporting cells of the organ of Corti and adjace nt epithelia. Their distribution closely parallels the boundaries of t he epithelial gap junction system, implying a role in cochlear potassi um and pH homeostasis. CBP-15 was recently shown to be identical to on comodulin, the mammalian beta-parvalbumin, heretofore documented only in the placenta and neoplasms. Expression of this small calcium-bindin g protein in the OC is restricted to the outer hair cells, where it ma y function as a calcium-dependent regulatory protein.