Organ of Corti-specific polypeptides: OCP-I and OCP-II

Two polypeptides, OCP-I and OCP-II, specific to the organ of Corti of the guinea pig and the rat, were detected by two-dimensional polyacrylamide gel electrophoresis. They were neither present in other inner ear structures, nor in other organs tested. The two polypeptides constitute a substantial portion of the total protein of the organ of Corti. Both inner and outer layer of the organ of Corti contained approximately equal amounts of OCP-I and OCP-II. The molecular weights of OCP-I and OCP-II are 37,000 and 22,500 daltons, respectively. The corresponding pI values are 4.9 and 5.1, respectively. In addition, actin and tubulin were detected in both layers of the organ of Corti.