期刊
BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES
卷 1768, 期 11, 页码 2882-2889出版社
ELSEVIER
DOI: 10.1016/j.bbamem.2007.08.011
关键词
cation transport; membrane; Na+/H+ exchanger; pH regulation
The Na+/H+ exchanger isoform 1 (NHE1) is an integral membrane protein that regulates intracellular pH by extruding an intracellular H+ in exchange for one extracellular Na+. In this study we examined the effect of site-specific mutagenesis on the pore-lining amino acid Phe 161 and effects of mutagenesis on the charged amino acids As159 and Asp172. There was no absolute requirement for a carboxyl side chain at amino acid Asp159 or Asp172. Mutation of Asp159 to Asn or Gln maintained or increased the activity of the protein. Similarly, for Asp172, substitution with a Gln residue maintained activity of the protein, even though substitution with an Asn residue was inhibitory. The Asp172Glu mutant possessed normal activity after correction for its aberrant expression and surface targeting. Replacement of Phe 161 with a Leu demonstrated that it was not irreplaceable in NHE1 function. However, the mutation Phe161lys inhibited NHE1 function, while the Phe161Ala mutation caused altered NHE1 targeting and expression levels. Our results show that these three amino acids, while being important in NHE1 function, are not irreplaceable. This study demonstrates that multiple substitutions at a single amino acid residue may be necessary to get a clearer picture membrane protein function. (c) 2007 Elsevier B.V All rights reserved.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据