GATING OF INWARDLY RECTIFYING K+ CHANNELS LOCALIZED TO A SINGLE NEGATIVELY CHARGED RESIDUE
GATING OF INWARDLY RECTIFYING K+ CHANNELS LOCALIZED TO A SINGLE NEGATIVELY CHARGED RESIDUE
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DOI：
10.1038/371246a0
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发表时间：
1994-09-15
期刊：
影响因子：
64.8
通讯作者：
BROWN, AM
中科院分区：
文献类型：
--
作者：
WIBLE, BA;TAGLIALATELA, M;BROWN, AM
内向整流K+通道(IRK)优先在内向传导电流。这种内向整流有两个组成部分：细胞内镁离子(mg-I(2+))(1-7)的电压依赖性阻断和本征门控(8，9)。此通道家族中的两个成员，IRK1(参见10)和ROMK1(参考文献11)，对Mg-I(2+)的亲和力有显著差异(参考文献11)。12)。我们发现IRK1和ROMK1在电压依赖门控方面存在差异，并通过大规模和定点突变寻找门控结构。我们发现，在可能的跨膜结构域M2中，IRK1中的天冬氨酸(D)改变为ROMK1中相应的天冬酰胺(N)，控制着门控表型。IRK1突变D172N产生类ROMK1门控，而ROMK1-N171D反向突变产生类IRK1门控。因此，单个带负电荷的残基似乎是门控的关键决定因素。
INWARDLY rectifying K+ channels (IRKs) conduct current preferentially in the inward direction. This inward rectification has two components: voltage-dependent blockade by intracellular Mg2+ (Mg-i(2+))(1-7) and intrinsic gating(8,9). Two members of this channel family, IRK1 (ref. 10) and ROMK1 (ref. 11), differ markedly in affinity for Mg-i(2+) (ref. 12). We found that IRK1 and ROMK1 differ in voltage-dependent gating and searched for the gating structure by large-scale and site-directed mutagenesis. We found that a single amino-acid change within the putative transmembrane domain M2, aspartate (D) in IRK1 to the corresponding asparagine (N) in ROMK1, controls the gating phenotype. Mutation D172N in IRK1 produced ROMK1-like gating whereas the reverse mutation in ROMK1-N171D-produced IRK1-like gating. Thus, a single negatively charged residue seems to be a crucial determinant of gating.