ATP-sensitive potassium channels in adult mouse skeletal muscle: Characterization of the ATP-binding site
ATP-sensitive potassium channels in adult mouse skeletal muscle: Characterization of the ATP-binding site
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成年小鼠骨骼肌中 ATP 敏感钾通道：ATP 结合位点的表征
DOI：
10.1007/bf01869152
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发表时间：
1989
期刊：
影响因子：
--
通讯作者：
B. Neumcke
中科院分区：
文献类型：
--
作者：
R. Weik;B. Neumcke
本文研究了从小鼠趾肌纤维上切下的由内而外的膜片上的单个K+选择性通道。在对称的160 mm KCl溶液中，电导为74 pS的通道被10 μm的ATP可逆地阻断，因此被鉴定为ATP敏感性K+通道。内腺苷、腺嘌呤和胸腺嘧啶也可逆地阻断该通道，但不被胞嘧啶和尿嘧啶阻断。当可逆通道阻滞剂存在于内部NaCl而不是KCl溶液中时，其功效更高。内液中加入0.5mm氯胺T、50 mm过氧化氢或2 mm乙基马来酰亚胺（NEM）等巯基修饰物质后，ATP敏感性K ~+通道被不可逆地抑制。大电导钙激活的K+通道不受这些试剂的影响。NEM对ATP敏感性K+通道的不可逆抑制作用可被1 mm内ATP阻断。结果表明，内部Na+离子增加ATP敏感的K+通道的ATP和其他可逆的通道阻滞剂的亲和力和功能上重要的SH-组位于或附近的ATP结合位点。
SummarySingle K+-selective channels were studied in excised inside-out membrane patches from dissociated mouse toe muscle fibers. Channels of 74 pS conductance in symmetrical 160mm KCl solutions were blocked reversibly by 10 μm internal ATP and thus identified as ATP-sensitive K+ channels. The channels were also blocked reversibly bymm concentrations of internal adenosine, adenine and thymine, but not by cytosine and uracil. The efficacy of the reversible channel blockers was higher when they were present in internal NaCl instead of KCl solutions. An irreversible inhibition of ATP-sensitive K+ channels was observed after application of several sulphydryl-modifying substances in the internal solution: 0.5mm chloramine-T, 50mm hydrogen peroxide or 2mmn-ethylmaleimide (NEM). Largeconductance Ca-activated K+ channels were not affected by these reagents. The presence of 1mm internal ATP prevents the irreversible inhibition of ATP-sensitive K+ channels by NEM. The results suggest that internal Na+ ions increase the affinity of the ATP-sensitive K+ channel to ATP and to other reversible channel blockers and that a functionally important SH-group is located at or near the ATP-binding site.