Functional regulation of BK potassium channels by γ1 auxiliary subunits.
Many K(+) channels are oligomeric complexes with intrinsic structural symmetry arising from the homo-tetrameric core of their pore-forming subunits. Allosteric regulation of tetramerically symmetric proteins, whether by intrinsic sensing domains or associated auxiliary subunits, often mirrors the fourfold structural symmetry. Here, through patch-clamp recordings of channel population ensembles and also single channels, we examine regulation of the Ca(2+)- and voltage-activated large conductance Ca(2+)-activated K(+) (BK) channel by associated γ1-subunits. Through expression of differing ratios of γ1:α-subunits, the results reveal an all-or-none functional regulation of BK channels by γ-subunits: channels either exhibit a full gating shift or no shift at all. Furthermore, the γ1-induced shift exhibits a state-dependent labile behavior that recapitulates the fully shifted or unshifted behavior. The γ1-induced shift contrasts markedly to the incremental shifts in BK gating produced by 1-4 β-subunits and adds a new layer of complexity to the mechanisms by which BK channel functional diversity is generated.
['Gonzalez-Perez|Vivian|V|', 'Xia|Xiao-Ming|XM|', 'Lingle|Christopher J|CJ|']
D000494:Allosteric Regulation D000818:Animals D006801:Humans D015640:Ion Channel Gating D051379:Mice D008954:Models, Biological D009363:Neoplasm Proteins D021122:Protein Subunits D013997:Time Factors D014982:Xenopus laevis
Slo1 channels allostery asymmetry