The structure of the potassium channel:: Molecular basis of K+ conduction and selectivity
The structure of the potassium channel:: Molecular basis of K+ conduction and selectivity
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DOI：
10.1126/science.280.5360.69
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发表时间：
1998-04-03
期刊：
影响因子：
56.9
通讯作者：
MacKinnon, R
中科院分区：
文献类型：
--
作者：
Doyle, DA;Cabral, JM;MacKinnon, R
lividans链霉菌的钾通道是一种完整的膜蛋白，其序列与所有已知的K+通道相似，特别是在孔隙区域。数据为3.2埃x射线分析表明,四个相同的子单元创建一个倒圆锥形帐篷,或锥,抱着选择性过滤孔隙的外端,狭窄的选择性过滤器只有12埃长,而其余的毛孔更广泛和内衬疏水性氨基酸,大型水腔和螺旋偶极子定位,克服静电扰动的离子在双分子层的中心孔。来自K+通道特征序列的主链羰基氧原子排列在选择性过滤器上，由于结构约束，选择性过滤器打开以配位K+离子，而不是较小的Na+离子。选择性滤光片含有两个相距约7.5埃的K+离子。这种结构通过利用静电斥力来克服K+离子和选择性填料之间的吸引力来促进离子传导。孔的结构建立了选择性K+传导的物理原理。
The potassium channel from Streptomyces lividans is an integral membrane protein with sequence similarity to all known K+ channels, particularly in the pore region. X-ray analysis with data to 3.2 angstroms reveals that four identical subunits create an inverted teepee, or cone, cradling the selectivity filter of the pore in its outer end, The narrow selectivity filter is only 12 angstroms long, whereas the remainder of the pore is wider and lined with hydrophobic amino acids, A large water-filled cavity and helix dipoles are positioned so as to overcome electrostatic destabilization of an ion in the pore at the center of the bilayer. Main chain carbonyl oxygen atoms from the K+ channel signature sequence line the selectivity filter, which is held open by structural constraints to coordinate K+ ions but not smaller Na+ ions. The selectivity filter contains two K+ ions about 7.5 angstroms apart. This configuration promotes ion conduction by exploiting electrostatic repulsive forces to overcome attractive forces between K+ ions and the selectivity filler. The architecture of the pore establishes the physical principles underlying selective K+ conduction.