The role of NH2-terminal positive charges in the activity of inward rectifier KATP channels
The role of NH2-terminal positive charges in the activity of inward rectifier KATP channels
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DOI：
10.1085/jgp.20028621
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发表时间：
2002-09-01
影响因子：
3.8
通讯作者：
Nichols, CG
中科院分区：
文献类型：
--
作者：
Cukras, CA;Jeliazkova, I;Nichols, CG
大约一半的内向整流(KIR)通道的NH2末端可以在不显著改变通道功能的情况下被删除，但当超过30个保守残基时，第一个跨膜结构域(M1)被移除时，活性就会丧失。用丙氨酸系统地替换Kir6.2的NH2末端的正电荷，发现了几个残基，它们在中和时会影响通道功能。某些突变(R4A、R5A、R16A、R27A、R39A、K47A、R50A、R54A、K67A)改变开放概率，而一组重叠的突变(R16A、R27A、K39A、K47A、R50A、R54A、K67A)改变ATP敏感性。对后一组的进一步分析将由于开放状态稳定性改变而改变ATP敏感性的突变(R16A、K39A、K67A)与可能直接影响ATP结合的突变(K47A、R50A、R54A)区分开来。这些数据有助于确定KIR通道功能的结构决定因素，并提出NH2末端可能的结构基序，以及NH2末端与通道延伸的细胞质COOH末端的关系。
Approximately half of the NH2 terminus of inward rectifier (Kir) channels can be deleted without significant change in channel function, but activity is lost when more than similar to30 conserved residues before the first membrane spanning domain (M1) are removed. Systematic replacement of the positive charges in the NH2 terminus of Kir6.2 with alanine reveals several residues that affect channel function when neutralized. Certain mutations (R4A, R5A, R16A, R27A, R39A, K47A, R50A, R54A, K67A) change open probability, whereas an overlapping set of mutants (R16A, R27A, K39A, K47A, R50A, R54A, K67A) change ATP sensitivity. Further analysis of the latter set differentiates mutations that alter ATP sensitivity as a consequence of altered open state stability (R16A, K39A, K67A) from those that may affect ATP binding directly (K47A, R50A, R54A). The data help to define the structural determinants of Kir channel function, and suggest possible structural motifs within the NH2 terminus, as well as the relationship of the NH2 terminus with the extended cytoplasmic COOH terminus of the channel.