Molecular Physiology of Vertebrate Na[sup]+[r]/H[sup]+[r] Exchangers.
Wakabayashi, Shigeo, Munekazu Shigekawa, and Jacques Pouyssegur.
Dept. of Molecular Physiology, National Cardiovascular Center Research
Institute, Suita, Osaka, Japan and Centre de Biochimie, Centre National de la
Rechereche Scientifique, Universite de Nice, Nice, France.
APStracts 2:0041P, 1996.
ABSTRACT
This review describes recent progress concerning the molecular aspects of the
Na[sup]+[r]/H[sup]+[r] exchanger. The Na[sup]+[r]/H[sup]+[r] exchanger is an
important regulator for intracellular pH, cell volume, and transepithelial
Na[sup]+[r] transport. It exists in virtually all cells with cell type-
dependent pattern of isoform expression, and it is regulated in response to a
variety of extracellular stimuli, among them not only agonists such as growth
factors and hormones but also mechanical stimuli such as osmotic stress and
cell spreading. Thus this transporter is also an excellent model to study the
signal transduction. Since the first molecular cloning of the
Na[sup]+[r]/H[sup]+[r] exchanger, detailed studies revealed many interesting
features of this transporter. At present, at least five different isoforms of
the Na[sup]+[r]/H[sup]+[r] exchanger are known. These isoforms differ in
tissue localization, sensitivity of inhibitors, and mode of transcriptional
and posttranscriptional regulation, allowing them to participate in different
physiological processes. We have only started to understand an intriguing
mechanism underlying these functional differences among the exchanger
isoforms. Because the Na[sup]+[r]/H[sup]+[r] exchanger is relatively simple in
terms of its kinetic features, e.g., a simple 1:1 stoichiometry of Na[sup]+[r]
and H[sup]+[r] and no input of metabolic energy such as ATP hydrolysis, the
study of its structural and mechanistic aspects would also serve as a good
model to understand the general mechanism of various ion transporters.
APS Manuscript Number P21-6.
Article publication pending January 1997, Physiological Reviews.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 13 November 1996