Novel concatenated tandem constructs reveal 3 distinct types of subunit stoichiometry in BK channel modulation

Abstract

The large-conductance, Ca2+-activated K+ (BK) channels consist of the Ca2+- and voltage-sensing and pore-forming α (BKα) subunits and regulatory auxiliary β or γ subunits. Concatenated tandem constructs have been proved to be necessary and powerful in understanding the subunit stoichiometry of K+ channel gating and regulation by constraining the stoichiometry and mutation of individual subunits. In order to investigate the molecular mechanisms of the atypical “all-or-none” modulatory function of the γ subunits and the subunit stoichiometry of BK channel gating, we have taken a novel strategy and generated functional concatenated tandem constructs containing 2 or 4 copies of the BKα subunits by splicing BKα into 2 protein constructs that can be co-expressed to form functional channels.