Calcium-activated potassium channel subunit beta-1 (KCNMB1)

The Calcium-activated potassium channel subunit beta-1 (KCNMB1) is a specialized auxiliary protein that regulates the large-conductance calcium-activated potassium (BK) channel, primarily within vascular and visceral smooth muscle cells (UniProt: Q12791). It functions by dramatically increasing the channel's sensitivity to intracellular calcium and membrane voltage, allowing the channel to open under physiological conditions that would otherwise be insufficient for the alpha subunit alone (PubMed: 15123943). This activation promotes potassium efflux, leading to membrane hyperpolarization and the subsequent closure of voltage-gated calcium channels, which results in smooth muscle relaxation and vasodilation (PubMed: 11069971). Clinically, KCNMB1 is a major determinant of vascular tone; for instance, the E65K gain-of-function polymorphism in humans is associated with protection against systemic hypertension (PubMed: 15654337). Pharmacologically, the subunit is a target for vasodilators and bronchodilators, as its presence is required for the full effect of certain BK channel openers like BMS-204352 and various natural modulators (PubMed: 11160614, PubMed: 23064403).

Other names

BK channel subunit beta-1Maxi K channel subunit beta-1K(VCA)beta-1Charybdotoxin receptor subunit beta-1BKbeta1KCNMB

Acts as an allosteric modulator that increases the calcium sensitivity and shifts the voltage-dependence of activation of the pore-forming alpha subunit (KCNMA1) toward more physiological (negative) membrane potentials.