Allosteric linkage between voltage and Ca(2+)-dependent activation of BK-type mslo1 K(+) channels.

摘要: The activation of BK type Ca(2+)-activated K(+) channels depends on both voltage and Ca(2+). We studied three point mutations in the putative sensor S4 or S4-S5 linker regions mslo1 to explore relationship between Ca(2+) activating channel. These reduced steepness open probability - (P(o) V) relation increased shift P(o) V relations axis response increases calcium concentration. It is striking that these two effects were reciprocally related for all mutations, despite different other aspects dependence channel gating. This reciprocal suggests strongly free energy contributions provided by binding are simply additive. conclude sites sensors do not directly interact. Rather they affect opening through an allosteric mechanism, influencing conformational change closed conformations. changed channel's with little effect its affinitiy.