KCNMB3
Domain
Isoform 4 cytoplasmic N-terminal domain participates in the partial inactivation of KCNMA1, possibly by binding to a receptor site.
The extracellular domain forms gates to block ion permeation, providing a mechanism by which current can be rapidly diminished upon cellular repolarization.
Function
Regulatory subunit of the calcium activated potassium KCNMA1 (maxiK) channel. Modulates the calcium sensitivity and gating kinetics of KCNMA1, thereby contributing to KCNMA1 channel diversity. Alters the functional properties of the current expressed by the KCNMA1 channel. Isoform 2, isoform 3 and isoform 4 partially inactivate the current of KCNBMA. Isoform 4 induces a fast and incomplete inactivation of KCNMA1 channel that is detectable only at large depolarizations. In contrast, isoform 1 does not induce detectable inactivation of KCNMA1. Two or more subunits of KCNMB3 are required to block the KCNMA1 tetramer.
Post-translational modifications
N-glycosylated.
The extracellular domain contains disulfide bond essential for the gating mechanism.
Sequence Similarities
Belongs to the KCNMB (TC 8.A.14.1) family. KCNMB3 subfamily.
Tissue Specificity
Isoform 1, isoform 3 and isoform 4 are widely expressed. Isoform 2 is expressed placenta, pancreas, kidney and heart. Isoform 1 and isoform 3 are highly expressed in pancreas and testis.
Cellular localization
- Membrane
- Multi-pass membrane protein
Alternative names
KCNMB2, KCNMBL, KCNMB3, Calcium-activated potassium channel subunit beta-3, BK channel subunit beta-3, Charybdotoxin receptor subunit beta-3, K(VCA)beta-3, Maxi K channel subunit beta-3, Slo-beta-3, BKbeta3, Hbeta3