Suppr超能文献

钠钾ATP酶跨膜螺旋M3氨基末端部分中Ile279、Ile283、Glu284、His285、Phe286和His288改变的功能后果。

Functional consequences of alterations to Ile279, Ile283, Glu284, His285, Phe286, and His288 in the NH2-terminal part of transmembrane helix M3 of the Na+,K(+)-ATPase.

作者信息

Toustrup-Jensen Mads, Vilsen Bente

机构信息

Department of Physiology, University of Aarhus, Ole Worms Allé 160, DK-8000 Aarhus C, Denmark.

出版信息

J Biol Chem. 2003 Oct 3;278(40):38653-64. doi: 10.1074/jbc.M305521200. Epub 2003 Jul 7.

Abstract

Mutations Ile279 --> Ala, Ile283 --> Ala, Glu284 --> Ala, His285 --> Ala, His285 --> Lys, His285 --> Glu, Phe286 --> Ala, and His288 --> Ala in transmembrane helix M3 of the Na+,K(+)-ATPase were studied. Except for His285 --> Ala, these mutations were compatible with cell viability, permitting analysis of their effects on the overall and partial reactions of the Na+,K(+)-transport cycle. In Ile279 --> Ala and Ile283 --> Ala, the E1 form accumulated, whereas in His285 --> Lys and His285 --> Glu, E1P accumulated. Phe286 --> Ala displaced the conformational equilibria of dephosphoenzyme and phosphoenzyme in parallel in favor of E2 and E2P, respectively, and showed a unique enhancement of the E1P --> E2P transition rate. These effects suggest that M3 undergoes significant rearrangements in relation to E1-E2 and E1P-E2P conformational changes. Because the E1-E2 and E1P-E2P conformational equilibria were differentially affected by some of the mutations, the phosphorylated conformations seem to differ significantly from the dephospho forms in the M3 region. Mutation of His285 furthermore increased the Na(+)-activated ATPase activity in the absence of K+ ("Na(+)-ATPase activity"). Ile279 --> Ala, Ile283 --> Ala, and His288 --> Ala showed reduced Na+ affinity of the E1 form. The rate of Na(+)-activated phosphorylation from ATP was reduced in Ile279 --> Ala and Ile283 --> Ala, and these mutants showed evidence similar to Glu329 --> Gln of destabilization of the Na(+)-occluded state.

摘要

对钠钾ATP酶跨膜螺旋M3中的Ile279→Ala、Ile283→Ala、Glu284→Ala、His285→Ala、His285→Lys、His285→Glu、Phe286→Ala和His288→Ala突变进行了研究。除His285→Ala外,这些突变与细胞活力相容,从而能够分析它们对钠钾转运循环的整体和部分反应的影响。在Ile279→Ala和Ile283→Ala中,E1形式积累,而在His285→Lys和His285→Glu中,E1P积累。Phe286→Ala分别平行地改变了脱磷酸酶和磷酸酶的构象平衡,有利于E2和E2P,并且显示出E1P→E2P转变速率的独特增强。这些效应表明,M3相对于E1-E2和E1P-E2P构象变化经历了显著的重排。由于E1-E2和E1P-E2P构象平衡受到某些突变的不同影响,磷酸化构象在M3区域似乎与脱磷酸形式有显著差异。此外,His285的突变在没有K+的情况下增加了钠激活的ATP酶活性(“钠ATP酶活性”)。Ile279→Ala、Ile283→Ala和His288→Ala显示出E1形式对Na+的亲和力降低。Ile279→Ala和Ile283→Ala中ATP的钠激活磷酸化速率降低,并且这些突变体显示出类似于Glu329→Gln的钠封闭状态不稳定的证据。

文献AI研究员

20分钟写一篇综述,助力文献阅读效率提升50倍。

立即体验

用中文搜PubMed

大模型驱动的PubMed中文搜索引擎

马上搜索

文档翻译

学术文献翻译模型,支持多种主流文档格式。

立即体验