A6细胞中Na⁺/H⁺交换体NHE1亚型的生物合成与细胞表面转运
Biosynthesis and cell surface delivery of the NHE1 isoform of Na+/H+ exchanger in A6 cells.
作者信息
Coupaye-Gerard B, Bookstein C, Duncan P, Chen X Y, Smith P R, Musch M, Ernst S A, Chang E B, Kleyman T R
机构信息
Department of Medicine, University of Pennsylvania, Philadelphia, USA.
出版信息
Am J Physiol. 1996 Nov;271(5 Pt 1):C1639-45. doi: 10.1152/ajpcell.1996.271.5.C1639.
The Na+/H+ exchanger isoform NHE1 is localized to the basolateral membrane of renal and intestinal epithelia. We examined the plasma membrane distribution, biosynthesis, and cell surface delivery of NHE1 in A6 epithelia. NHE1 was localized to the basolateral membrane. Studies of NHE1 biosynthesis with a pulse-chase protocol demonstrated that a core glycosylated, endoglycosidase H-sensitive, 90-kDa NHE1 was present 0-5 h into the chase period and that mature 110-kDa NHE1 was present 1-24 h into the chase period. Studies of plasma membrane delivery of newly synthesized NHE1 demonstrated that the 90-kDa NHE1 was detected at both apical and basolateral membranes 2-5 h into the chase period. The 110-kDa NHE1 was observed at the basolateral membrane 5-24 h into the chase period. These results suggest that NHE1 is expressed primarily at the basolateral membrane of A6 cells, that core glycosylated NHE1 is delivered to the plasma membrane in a nonpolarized manner, and that nature 110-kDa NHE1 is delivered to the basolateral membrane.
钠离子/氢离子交换体亚型NHE1定位于肾和肠上皮细胞的基底外侧膜。我们研究了A6上皮细胞中NHE1的质膜分布、生物合成及细胞表面转运。NHE1定位于基底外侧膜。采用脉冲追踪法对NHE1生物合成的研究表明，在追踪期0 - 5小时出现了一种核心糖基化、对内切糖苷酶H敏感的90 kDa的NHE1，在追踪期1 - 24小时出现了成熟的110 kDa的NHE1。对新合成的NHE1质膜转运的研究表明，在追踪期2 - 5小时，在顶端膜和基底外侧膜均检测到90 kDa的NHE1。在追踪期5 - 24小时，在基底外侧膜观察到110 kDa的NHE1。这些结果表明，NHE1主要在A6细胞的基底外侧膜表达，核心糖基化的NHE1以非极化方式转运至质膜，而天然的110 kDa的NHE1转运至基底外侧膜。
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