The KCNMB1 gene, located on chromosome 5q34, contains four exons and encodes the 191 amino-acid protein MaxiKbeta subunit 1 (also designated calcium-activated potassium channel beta subunit, BK channel beta subunit, Slo-beta and KVCAbeta). MaxiKbeta subunit 1 consists of two putative transmembrane domains, an extracellular loop containing three consensus sequences for N-linked glycosylation and four cysteine residues that might form disulfide bridges. MaxiKbeta subunit 1, one of four subunits in the MaxiKbeta family, is expressed predominately in smooth muscle tissue but is also found in brain, liver and lymphatic tissues. MaxiKbeta subunit 1 associates with MaxiKalpha to form a calcium-activated potassium channel (also designated MaxiK and BK channel). MaxiKbeta subunit 1 increases the sensitivity of the MaxiKalpha to calcium and voltage. The MaxiKalpha/beta1 channel is the most sensitive of all Maxi channels to calcium. MaxiKbeta plays an important role in vasoregulation by controlling the sensitivity of MaxiK channels to calcium, which leads to the proper amount of arterial relaxation.Synonyms: BK channel beta-1, Calcium-activated potassium channel subunit beta-1, Charybdotoxin receptor subunit beta-1, K VCAbeta-1, Maxi K channel beta-1, Slo-beta-1, subfamily M beta-1