Determinants of cardiac Na+/Ca2+ exchanger temperature dependence:: NH2-terminal transmembrane segments
Determinants of cardiac Na+/Ca2+ exchanger temperature dependence:: NH2-terminal transmembrane segments
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DOI：
10.1152/ajpcell.00558.2001
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发表时间：
2002-08-01
影响因子：
5.5
通讯作者：
Tibbits, GF
中科院分区：
文献类型：
--
作者：
Marshall, C;Elias, C;Tibbits, GF
心脏Na+/Ca 2+交换器（NCX）在鳟鱼表现出深刻的温度敏感性相比，哺乳动物NCX。在这项研究中，我们试图表征NCX分子的区域，负责其温度敏感性。使用野生型鳟鱼和犬NCX cDNA构建嵌合NCX分子，并在非洲爪蟾卵母细胞中表达。在7、14和30摄氏度下，使用巨大切除贴片技术测量了NCX介导的电流。通过使用这种方法，发现NCX的差分温度依赖性驻留在分子的NH 2-末端区域内。具体地说，我们发现Na+/Ca ~（2+）交换活化的差异能的75%是由前四个跨膜片段的序列差异引起的，其余部分是由第五个跨膜片段和交换抑制肽位点引起的。
The cardiac Na+/Ca2+ exchanger (NCX) in trout exhibits profoundly lower temperature sensitivity in comparison to the mammalian NCX. In this study, we attempt to characterize the regions of the NCX molecule that are responsible for its temperature sensitivity. Chimeric NCX molecules were constructed using wild-type trout and canine NCX cDNA and expressed in Xenopus oocytes. NCX-mediated currents were measured at 7, 14, and 30degrees C using the giant excised-patch technique. By using this approach, the differential temperature dependence of NCX was found to reside within the NH2-terminal region of the molecule. Specifically, we found that similar to75% of the Na+/Ca2+ exchange differential energy of activation is attributable to sequence differences in the region that include the first four transmembrane segments, and the remainder is attributable to transmembrane segment five and the exchanger inhibitory peptide site.