The Journal of Biochemistry
Online ISSN : 1756-2651
Print ISSN : 0021-924X
Properties of the Na+/H+ Antiporter in Vibrio parahaemolyticus
Teruo KurodaToshi ShimamotoKei InabaTakashi KayaharaMasaaki TsudaTomofusa Tsuchiya
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1994 Volume 115 Issue 6 Pages 1162-1165


The properties of the Na+/H+ antiporter in Vibrio parahaemolyticus, a slightly halophilic bacterium, were investigated using everted membrane vesicles. It appears that at least two Na+/H+ antiporters are present, one that is pH-dependent and one that is pH-independent. These two antiporters appear to correspond to the NhaA and NhaB antiporters of Escherichia coli, respectively. It seems that amiloride strongly inhibits the pH-dependent antiporter. Na+ is the best substrate for both of the two V. parahaemolyticus antiporters. Li+ is a poorer substrate and K+ is not a substrate. No K+/H+ antiport activity was detected in membrane vesicles of this organism. The Na+(Li+)/H+ antiport activity greatly increased with an increase in pH of the assay medium. pH did not affect the Km value of the Na+/H+ antiport, but it did increase the Vmax.

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