Topogenic properties of transmembrane segments of Arabidopsis thaliana NHX1 reveal a common topology model of the Na+/H+ exchanger family.
Topogenic properties of transmembrane segments of Arabidopsis thaliana NHX1 reveal a common topology model of the Na+/H+ exchanger family.
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DOI：
10.1093/jb/mvi132
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发表时间：
2005-10
影响因子：
2.7
通讯作者：
Yoko Sato;M. Sakaguchi
中科院分区：
文献类型：
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作者：
Yoko Sato;M. Sakaguchi
利用无细胞系统研究了拟南芥Na +/H+交换器亚型1（AtNHX 1）跨膜（TM）片段的拓扑结构。尽管在人Na（+）/H（+）交换器（NHE）家族中发现的信号肽缺失，但N-末端疏水片段被有效地插入膜中，并且具有取决于下一个TM片段的N-末端管腔拓扑结构。两个N-末端TM片段具有与人NHE 1的TM 2和TM 3相同的拓扑结构。相反，当信号肽（表示为TM 1）缺失时，人NHE 1的TM 2和TM 3没有获得正确的拓扑结构。此外，有三个疏水片段具有与人NHE 1的TM 9-H10-TM 10片段相同的拓扑特性，其具有一个内腔环（H10）和两个侧翼TM片段（TM 9和TM 10）。这些数据表明，植物NHX同种型可以形成为人类NHE家族提出的常见膜拓扑结构，即使它不具有信号肽。
The membrane topology of the Arabidopsis thaliana Na(+)/H(+) exchanger isoform 1 (AtNHX1) was investigated by examining the topogenic function of transmembrane (TM) segments using a cell-free system. Even though the signal peptide found in the human Na(+)/H(+) exchanger (NHE) family is missing, the N-terminal hydrophobic segment was efficiently inserted into the membrane and had an N-terminus lumen topology depending on the next TM segment. The two N-terminal TM segments had the same topology as those of TM2 and TM3 of human NHE1. In contrast, TM2 and TM3 of human NHE1 did not acquire the correct topology when the signal peptide (denoted as TM1) was deleted. Furthermore, there were three hydrophobic segments with the same topogenic properties as the TM9-H10-TM10 segments of human NHE1, which has one lumenal loop (H10) and two flanking TM segments (TM9 and TM10). These data indicate that the plant NHX isoforms can form the common membrane topology proposed for the human NHE family, even though it does not have a signal peptide.