KCNMB3
Description
The KCNMB3 (potassium calcium-activated channel subfamily M regulatory beta subunit 3) is a protein-coding gene located on chromosome 3.
Calcium-activated potassium channel subunit beta-3 is a protein that in humans is encoded by the KCNMB3 gene. MaxiK channels are large conductance, voltage and calcium-sensitive potassium channels which are fundamental to the control of smooth muscle tone and neuronal excitability. MaxiK channels can be formed by 2 subunits: the pore-forming alpha subunit and the modulatory beta subunit. The protein encoded by this gene is an auxiliary beta subunit which may partially inactivate or slightly decrease the activation time of MaxiK alpha subunit currents. At least four transcript variants encoding four different isoforms have been found for this gene.
KCNMB3, also known as BK channel subunit beta-3, is a regulatory subunit of the calcium-activated potassium channel KCNMA1 (maxiK). It modulates the calcium sensitivity and gating kinetics of KCNMA1, contributing to the diversity of KCNMA1 channels. KCNMB3 alters the functional properties of the current expressed by the KCNMA1 channel. Isoforms 2, 3, and 4 partially inactivate the current of KCNBMA, with isoform 4 inducing a fast and incomplete inactivation of the KCNMA1 channel, detectable only at large depolarizations. Isoform 1 does not induce detectable inactivation of KCNMA1. Two or more subunits of KCNMB3 are required to block the KCNMA1 tetramer, indicating an interaction with the KCNMA1 tetramer. There are likely 4 molecules of KCMNB3 per KCNMA1 tetramer.
KCNMB3 is also known as BKBETA3, HBETA3, K(VCA)BETA-3, KCNMB2, KCNMBL, SLO-BETA-3, SLOBETA3.
