Auxiliary protein of the large-conductance, voltage and calcium-activated potassium channel (BK alpha). Modulates gating properties by producing a marked shift in the BK channel's voltage dependence of activation in the hyperpolarizing direction, and in the absence of calcium. KCNU1 channel auxiliary protein. May modulate KCNU1 gating properties.
Subcellular locations: Cell membrane
Expression at the cell surface may require the presence of KCNU1.
Mainly expressed in testis and skeletal muscle.