DETECTION OF A BETA-PARVALBUMIN ISOFORM IN THE MAMMALIAN INNER-EAR

A small, acidic calcium-binding protein (CBP-15) has been detected in the guinea pig organ of Corti, the auditory receptor organ. The appare nt molecular weight (15,000) and very low isoelectric point (pI approx imate to 3.1) suggest that CBP-15 is a beta-parvalbumin isoform. Consi stent with this hypothesis, CBP-15 exhibits extreme homology to the ma mmalian oncofetal parvalbumin called oncomodulin. Sequence data have n ow been obtained for 30 residues in the N-terminal third of CBP-15. Id entity with oncomodulin is observed at all 30 positions This finding c ould necessitate revision of the assumption that postnatal mammals uti lize a single alpha-parvalbumin isoform in muscle and nonmuscle settin gs alike. (C) 1995 Academic Press. Inc.