Hormonal regulation of the na+/k+ŻglhiddenŻ-atpase: mechanisms underlying
rapid and sustained changes in pump activity.
Ewart, H. Stephen, and Amira Klip.
Division of Cell Biology, The Hospital for Sick Children, 555
University Avenue, Toronto Ont. M5G 1X8, Canada, +Departments of
Paediatrics, Biochemistry and Physiology, University of Toronto
APStracts 2:0083C, 1995.
The sodium-potassium activated adenosinetriphosphatase (Na+/K+-ATPase;
Na+/K+-pump) is a ubiquitous plasma membrane enzyme that catalyses
the movement of K+ into cells in exchange for Na+. In addition it
provides the driving force for the transport of other solutes,
notably amino acids, sugar and phosphate. The regulation of Na+/K+
-ATPase in various tissues is under the control of a number of
circulating hormones which impart both short- and long-term control
over its activity. The molecular mechanisms by which hormones alter
Na+/K+-ATPase activity have only begun to be studied. In this review
we assess the acute and long-term actions of a number of hormones
(aldosterone, thyroid hormone, catecholamines, insulin, carbachol) on
the Na+/K+-pump. The long-term regulation exerted by thyroid hormone
and aldosterone is mediated by changes in gene expression. The short
-term regulation exerted by catecholamines is mediated by reversible
phosphorylation of the pump catalytic subunit. We examine recent
evidence supporting regulation of the pump by phosphorylation in vitro
and in intact cells. Finally, in some tissues the rapid action of
insulin, aldosterone, and carbachol involves changes in the
subcellular distribution of pump units.
Received 3 January 1995; accepted in final form 5 January 1995.
APS Manuscript Number C48-5.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 28 February 1995.