Positions of β2 and β3 subunits in the large-conductance calcium- and voltage-activated BK potassium channel.

ABSTRACT: Large-conductance voltage- and Ca(2+)-gated K(+) channels are negative-feedback regulators of excitability in many cell types. They are complexes of α subunits and of one of four types of modulatory β subunits. These have intracellular N- and C-terminal tails and two transmembrane (TM) helices, TM1 and TM2, connected by an ∼100-residue extracellular loop. Based on endogenous disulfide formation between engineered cysteines (Cys), we found that in β2 and β3, as in β1 and β4, TM1 is closest to αS1 and αS2 and TM2 is closest to αS0. Mouse β3 (mβ3) has seven Cys in its loop, one of which is free, and this Cys readily forms disulfides with Cys substituted in the extracellular flanks of each of αS0-αS6. We identified by elimination mβ3-loop Cys152 as the only free Cys. We inferred the disulfide-

SUBMITTER: Wu RS 

PROVIDER: S-EPMC3536527 | biostudies-literature | 2013 Jan

REPOSITORIES: biostudies-literature