Ishihara H, Welsh M J
Howard Hughes Medical Institute, Department of Internal Medicine, University of Iowa College of Medicine, Iowa City 52242, USA.
Am J Physiol. 1997 Oct;273(4):C1278-89. doi: 10.1152/ajpcell.1997.273.4.C1278.
ATP hydrolysis by the cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channel predicts that energy from hydrolysis might cause asymmetric transitions in the gating cycle. We found that 3-(N-morpholino)propanesulfonic acid (MOPS) blocked the open channel by binding to a site 50% of the way through the electrical field. Block by MOPS revealed two distinct states, O1 and O2, which showed a strong asymmetry during bursts of activity; the first opening in a burst was in the O1 state and the last was in the O2 state. Addition of a nonhydrolyzable nucleoside triphosphate prevented the transition to the O2 state and prolonged the O1 state. These data indicate that ATP hydrolysis by the nucleotide-binding domains drives a series of asymmetric transitions in the gating cycle. They also indicate that ATP hydrolysis changes the conformation of the pore, thereby altering MOPS binding.
囊性纤维化跨膜传导调节因子（CFTR）氯离子通道水解三磷酸腺苷（ATP）预示着水解产生的能量可能会在门控循环中引起不对称转变。我们发现3-（N-吗啉代）丙磺酸（MOPS）通过结合到电场中50%位置的位点来阻断开放通道。MOPS的阻断揭示了两种不同的状态，即O1和O2，在活动爆发期间它们表现出强烈的不对称性；爆发中的首次开放处于O1状态，最后一次开放处于O2状态。添加不可水解的核苷三磷酸可阻止向O2状态的转变并延长O1状态。这些数据表明，核苷酸结合结构域水解ATP会在门控循环中驱动一系列不对称转变。它们还表明，ATP水解会改变孔的构象，从而改变MOPS的结合。
