Accessory potassium channel protein which modulates the activity of the pore-forming alpha subunit. Alters the functional properties of Kv1.4 but not Kv1.1 or Kv1.5. Forms heteromultimeric complex with alpha subunits. Predominantly expressed in brain. Strongest expression in olfactory bulb and thalamic nuclei. Not detected in heart, spleen, lung, liver, skeletal muscle, kidney and testis. Alteration of functional properties of alpha subunit is mediated through N-terminal domain of beta subunit. Belongs to the shaker potassium channel beta subunit family.