Identification of the gate structure of ion channels

在1998年，麦金农集团和大门的结构部分的结构部分被直接演示。基于这一结构信息的一些突变，引入了两种Potassium通道（Kir2.1，KAT 1）。对于不受限制的Potassium Channels （Kir2.1）三个充电的居民存在于边缘螺旋和内部螺旋之间。negatively charged residues （Aspy D1152 y D1， Glu y D1153 y D1） were neutralized。我们开发了一种方法来评估表面潜力，从和弦行为的转变-电压曲线。It was found that Glu D1153-D1 modified the affinity of Mg-D12+-D1 ion and reduced the surface potential， thus decreasing the single channel conductance。When the concentration of external Mgy D12+イエD1 was increased the open channel blocking appeared。From the kinetic analyses of the single channel recordings under MgイD12+イエD1 blocking condition it was suggested that MgイD12+イエD1 ion in the blocked state inhibited the closure of the gate。在KAT 1通道a mutation in the C-terminal end of the pore helix （T256）改变了超极化的激活动力学。这被证明是，关闭状态之间的过渡率和开放状态之间的过渡率是可以怀疑的。

In 1998 the crystal structure of the potassium channel was elucidated by MacKinnon's group and the structural parts of the gate was directly demonstrated. Based on this structural information some mutations were introduced into two kinds of potassium channels (Kir2.1, KAT1). For the inwardly rectifying potassium channels (Kir2.1) three charged residues exist in the loop between the pore helix and the inner helix. The negatively charged residues (AspィイD1152ィエD1, GluィイD1153ィエD1) were neutralized. We developed a method to evaluate the surface potential from the shift of the chord conductance-voltage curves. It was found that GluィイD1153ィエD1 modified the affinity of MgィイD12+ィエD1 ion and reduced the surface potential, thus decreasing the single channel conductance. When the concentration of external MgィイD12+ィエD1 was increased the open channel blocking appeared. From the kinetic analyses of the single channel recordings under MgィイD12+ィエD1 blocking condition it was suggested that MgィイD12+ィエD1 ion in the blocked state inhibited the closure of the gate. In the KAT1 channel a mutation in the C-terminal end of the pore helix (T256) altered the activation kinetics upon hyperpolarization. It was revealed that the transition rate between the closed state and the open state was susceptible to the mutation.