Enables aldo-keto reductase (NADP) activity; potassium channel regulator activity; and transmembrane transporter binding activity. Involved in several processes, including NADPH oxidation; myoblast differentiation; and regulation of protein localization to cell surface. Located in cytosol; juxtaparanode region of axon; and pinceau fiber. Is extrinsic component of cytoplasmic side of plasma membrane. Part of potassium channel complex. Colocalizes with microtubule. Orthologous to human KCNAB2 (potassium voltage-gated channel subfamily A regulatory beta subunit 2). [provided by Alliance of Genome Resources, Apr 2022]