Ca+2-activated K+ channel subunit beta-2; BK channel subunit beta-2; BKbeta2; Hbeta2; Ca+2-activated K+ channel, subfamily M subunit beta-2; charybdotoxin receptor subunit beta-2; Hbeta3; K(VCA)beta-2; Maxi K channel subunit beta-2; Slo-beta-2 (KCNMB2)

Function

• regulatory subunit of the Ca+2-activated K+ channel KCNMA1
• modulates Ca+2 sensitivity & gating kinetics of KCNMA1, thus contributing to KCNMA1 channel diversity
• acts as a negative regulator that confers rapid & complete inactivation of KCNMA1 channel complex
• may participate in KCNMA1 inactivation in chromaffin cells of the adrenal gland or in hippocampal CA1 neurons
• interacts with KCNMA1 tetramer
• there are probably 4 molecules of KCMNB2 per KCNMA1 tetramer

Structure

• N-glycosylated
• the ball & chain domain mediates inactivation of KCNMA1; it occludes the conduction pathway of KCNMA1 channels, & comprises the pore-blocking ball domain (residues 1-17) & the chain domain (residues 20-45) linking it to the transmembrane segment
• the ball domain is made up of a flexible N-terminus anchored at a well ordered loop-helix motif
• the chain domain consists of a 4-turn helix with an unfolded linker at its C-terminus
• belongs to the KCNMB (TC 8.A.14.1) family, KCNMB2 subfamily

Compartment

membrane

Expression

• expressed in kidney, heart & brain
• highly expressed in ovary
• expressed at low level in other tissues

More general terms

• transmembrane 2 protein
• K+ channel subfamily M
• glycoprotein

Component of

• Ca+2-activated K+ channel

Database

• Entrez gene: http://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&cmd=Retrieve&dopt=Graphics&list_uids=10242
• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:10242
• OMIM: https://mirror.omim.org/entry/605214
• UniProt: http://www.uniprot.org/uniprot/Q9Y691.html