Mutation of His 834 in human anion exchanger 1 affects substrate binding.
Mutation of His 834 in human anion exchanger 1 affects substrate binding.
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DOI：
10.1016/j.bbamem.2010.01.019
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发表时间：
2010-05
期刊：
影响因子：
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通讯作者：
Shinya Takazaki;Y. Abe;Tomohiro Yamaguchi;Mikako Yagi;T. Ueda;D. Kang;N. Hamasaki
中科院分区：
文献类型：
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作者：
Shinya Takazaki;Y. Abe;Tomohiro Yamaguchi;Mikako Yagi;T. Ueda;D. Kang;N. Hamasaki
阴离子交换器1（AE 1或带3）负责红细胞膜上的Cl−-HCO 3 −交换。以前，我们表明，带3是固定在一个面向内的构象，通过特定的修饰His 834与DEPC，导致其阴离子转运活性的强烈抑制。为了阐明His 834的生理作用，我们评估了各种带3突变体的硫酸盐转运活性：His 834处的不同突变体和834周围的丙氨酸突变体（Lys 829-Phe 836）在酵母细胞膜中。His 834突变体的Km值是野生型的4-10倍，而Vmax值几乎不低于野生型。同时，周边丙氨酸突变体的Km值仅略有增加。这些数据表明，His 834是至关重要的硫酸根阴离子的有效结合，但不是由底物结合诱导的构象变化。
Anion exchanger 1 (AE1 or band 3) is responsible for Cl−–HCO3−exchange on erythrocyte membrane. Previously, we showed that band 3 is fixed in an inward-facing conformation by specific modification of His 834 with DEPC, resulting in a strong inhibition of its anion transport activity. To clarify the physiological role of His 834, we evaluated the sulfate transport activities of various band 3 mutants: different mutants at His 834 and alanine mutants of peripheral residues around 834 (Lys 829–Phe 836) in yeast cell membranes. The Kmvalues of the His 834 mutants were 4–10 times higher than that of the wild type, while their Vmaxvalues were barely lower than that of wild type. Meanwhile, the Kmvalues of the peripheral alanine mutants were only slightly increased. These data suggest that His 834 is critically important for the efficient binding of sulfate anion, but not for the conformational change induced by substrate binding.