Protein–protein interactions of a Kvβ subunit in the cochlea

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Abstract
Accessory subunits associated with voltage‐gated potassium (Kv) channels can influence the biophysical properties and promote the surface expression of channel‐forming α‐subunits. Previously, we cloned several α‐subunits and a β‐subunit from a cDNA library of the chicken cochlea. In the present study, we raised an antibody against the N‐terminus of chicken Kvβ1.1 (cKvβ1.1) and characterized the Kvβ‐related polypeptide in cochlear tissues and heterologous cells. The anti‐cKvβ1.1 antibody recognizes a 45‐kDa polypeptide in chick cochlear extracts as well as in Chinese hamster ovary (CHO) cells transfected with cKvβ1.1. The accessory subunit was localized to the ganglion cells of the chick cochlea using immunohistochemistry and in situ hybridization. Coimmunoprecipitation studies show that Kvβ1.1 interacts with Shaker channel members Kvα1.2 and 1.3, both of which colocalize with β to the cochlear ganglion cells. Additionally, coimmunoprecipitation studies show that Kvα1.2 and 1.3 interact with each other, suggesting that these ion channels are formed by heteromultimers. In comparison, Kvβ did not coprecipitate with a member of the Shal subfamily. The presence of Kvβ in the cochlea suggests that this subunit contributes to the modulation of auditory signals in the ganglion cells, presumably by regulating properties of inactivation as well as surface expression of Kvα channels.