Modulation of BK Channel Function by Auxiliary Beta and Gamma Subunits

The large-conductance, Ca2+- and voltage-activated K+ (BK) channel is ubiquitously expressed in mammalian tissues and displays diverse biophysical or pharmacological characteristics. This diversity is in part conferred by channel modulation with different regulatory auxiliary subunits. To date, two distinct classes of BK channel auxiliary subunits have been identified: beta subunits and. subunits gamma Modulation of BK channels by the four auxiliary beta (beta 1-beta 4) subunits has been well established and intensively investigated over the past two decades. The auxiliary gamma subunits, however, were identified only very recently, which adds a new dimension to BK channel regulation and improves our understanding of the physiological functions of BK channels in various tissues and cell types. This chapter will review the current understanding of BK channel modulation by auxiliary beta and gamma subunits, especially the latest findings.