Mammalian na+/h+ exchanger gene family: structure and function
studies.
Yun, C. H. Chris, Chung-Ming Tse, Samir K. Nath, Susan A. Levine,
Steven R. Brant, and Mark Donowitz.
Department of Medicine, GI Unit, The Johns Hopkins University
School of Medicine, Baltimore, Maryland 21205
APStracts 2:0056G, 1995.
Na+/H+ exchangers are integral plasma membrane proteins which exchange
extracellular Na+ for intracellular H+ with a stoichiometry of one
for one. They are inhibitable by the diuretic amiloride and have
multiple cellular functions, including intracellular pH homeostasis,
cell volume control and electroneutral NaCl absorption in epithelia.
The presence of multiple forms of the exchangers was demonstrated by
the recent cloning of four mammalian Na+/H+ exchangers, NHE1, NHE2,
NHE3 and NHE4. All these cloned Na+/H+ exchangers have 10-12 putative
transmembrane helices and a long cytoplasmic carboxyl domain. Despite
the structural similarity, these Na+/H+ exchanger isoforms differ in
their tissue distribution, kinetic characteristics and response to
external stimuli. The present review deals with the recent
developments in the molecular identification of Na+/H+ exchanger gene
family, the functional characteristics and the short-term regulation
of Na+/H+ exchange at molecular and cellular levels.
Received 17 January 1995; accepted in final form 21 March 1995.
APS Manuscript Number G127-5.
Article publication pending Am. J. Physiol. (Gastrointest. Liver
Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 4 April 1995.