TY - JOUR T1 - Distinct Sensitivity of Slo1 Channel Proteins to Ethanol JF - Molecular Pharmacology JO - Mol Pharmacol DO - 10.1124/mol.112.081240 SP - mol.112.081240 AU - Jianxi Liu AU - Anna Bukiya AU - Guruprasad Kuntamallappanavar AU - Aditya Singh AU - Alex Dopico Y1 - 2012/01/01 UR - http://molpharm.aspetjournals.org/content/early/2012/10/23/mol.112.081240.abstract N2 - Ethanol levels reached in circulation during moderate-heavy alcohol intoxication (50-100 mM) modify Ca2+- and voltage-gated K+ (BK) channel activity (NPo) eventually altering physiology and behavior. Ethanol action on BK NPo solely requires the channel-forming subunit (slo1) within a bare lipid environment. To identify the protein region(s) that confers ethanol-sensitivity to slo1, we tested the ethanol-sensitivity of heterologously expressed slo1 and structurally-related channels. Ethanol (50 mM) increased NPo of mslo1 and Ca2+-gated MthK, the later following channel reconstitution into phospholipid bilayers. In contrast, 50-100 mM ethanol failed to alter NPo of Na+/Cl--gated rslo2, H+-gated mslo3, and an mslo1/3 chimera engineered by joining the mslo1 region encompassing from N-terminus to S6 with the mslo3 cytosolic tail (CTD). Collectively, data indicate that the slo family canonical design, which combines a TM6 voltage-gated K+ channel (KV) core with CTDs that empower the channel with ion-sensing, does not necessarily render ethanol-sensitivity. In addition, the region encompassing from N-terminus to S0-S1 cytosolic loop (missing in MthK) is not necessary for ethanol action. Moreover, incorporation of both this region and an ion-sensing CTD to TM6 KV cores (design common to mslo1, mslo3, and mslo1/mslo3 chimera) is not sufficient for ethanol-sensitivity. Rather, a CTD containing Ca2+-sensing RCK domains is critical to bestow KV structures, whether of 2 (MthK) or 6 (slo1) TMs, with sensitivity to intoxicating ethanol levels. ER -