Voltage-gated K+ channels in the plasma membrane control the repolarization and the frequency of action potentials in neurons, muscles and other excitable cells. The KV gene family encodes more than 30 proteins that comprise the subunits of the K+ channels, and they vary in their gating and permeation properties, subcellular distribution and expression patterns. Functional KV channels assemble as tetramers consisting of pore-forming å subunits (KV), which include the KV1, KV2, KV3 and KV4 proteins, and accessory or KV-subunits that modify the gating properties of the coexpressed KV subunits. KV∫, also known as KCNAB1 (potassium voltage-gated channel, shaker-related subfamily, beta member 1), is a 419 amino acid accessory K+ channel protein that exists as three alternatively spliced isoforms and regulates the activity of the pore-forming å subunit. It is expressed in brain, with highest levels detected in caudate nucleus, hippocampus and thalamus.