Physiologic rationale for multiple sodium pump isoforms. Differential regulation of alpha 1 vs alpha 2 by ionic stimuli.
A number of important themes emerge from our compartmental analyses of Na,K-ATPase biosynthesis in response to ionic stimuli. The ubiquitous alpha 1 beta 1 type sodium pump evolved to generate and maintain transmembrane Na+ and K+ gradients, and there are cell-type specific mechanisms of increasing synthesis and decreasing degradation to control surface expression of this important "housekeeping" enzyme. Expression of alpha 2 beta-type sodium pumps may have evolved in cells designated as K+ storehouses to facilitate maintenance of extracellular K+ in the presence of K+ restriction. Finally, the specialized distribution of Na,K-ATPase (and related E1-E2 type pumps) along the renal epithelia allows for monitoring and fine control of extracellular K+ and Na+ (volume). Many interesting questions remain to be answered, and we now have the probes and techniques needed to answer them.
McDonough
A A
AA
Department of Physiology and Biophysics, University of Southern California School of Medicine, Los Angeles 90033.
Azuma
K K
KK
Lescale-Matys
L
L
Tang
M J
MJ
Nakhoul
F
F
Hensley
C B
CB
Komatsu
Y
Y
D000818:Animals; D006706:Homeostasis; D007527:Isoenzymes / Q000378:metabolism*; D007668:Kidney / Q000502:physiology; D008954:Models, Biological; D011188:Potassium / Q000378:metabolism* / Q000494:pharmacology; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism* / Q000502:physiology*
D007527:Isoenzymes; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium