Isozymes of the Na-K-ATPase: heterogeneity in structure, diversity in function

Isozymes of the Na-K-ATPase: heterogeneity in structure, diversity in function Abstract The Na-K-ATPase is characterized by a complex molecular heterogeneity that results from the expression and differential association of multiple isoforms of both its α- and β-subunits. At present, as many as four different α-polypeptides (α1, α2, α3, and α4) and three distinct β-isoforms (β1, β2, and β3) have been identified in mammalian cells. The stringent constraints on the structure of the Na pump isozymes during evolution and their tissue-specific and developmental pattern of expression suggests that the different Na-K-ATPases have evolved distinct properties to respond to cellular requirements. This review focuses on the functional properties, regulation, and possible physiological relevance of the Na pump isozymes. The coexistence of multiple α- and β-isoforms in most cells has hindered the understanding of the roles of the individual polypeptides. The use of heterologous expression systems has helped circumvent this problem. The kinetic characteristics of different Na-K-ATPase isozymes to the activating cations (Na + and K + ), the substrate ATP, and the inhibitors Ca 2+ and ouabain demonstrate that each isoform has distinct properties. In addition, intracellular messengers differentially regulate the activity of the individual Na-K-ATPase isozymes. Thus the regulation of specific Na pump isozymes gives cells the ability to precisely coordinate Na-K-ATPase activity to their physiological requirements. ouabain sodium pump protein kinases Footnotes Address for reprint requests: G. Blanco, Dept. of Cell Biology and Physiology, Washington Univ. School of Medicine, 660 S. Euclid Ave., St. Louis, MO 63110. Copyright © 1998 the American Physiological Society http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png AJP - Renal Physiology The American Physiological Society

Isozymes of the Na-K-ATPase: heterogeneity in structure, diversity in function

AJP - Renal Physiology, Volume 275 (5): F633 – Nov 1, 1998

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Publisher
The American Physiological Society
Copyright
Copyright © 2011 the American Physiological Society
ISSN
0363-6127
eISSN
1522-1466
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Abstract

Abstract The Na-K-ATPase is characterized by a complex molecular heterogeneity that results from the expression and differential association of multiple isoforms of both its α- and β-subunits. At present, as many as four different α-polypeptides (α1, α2, α3, and α4) and three distinct β-isoforms (β1, β2, and β3) have been identified in mammalian cells. The stringent constraints on the structure of the Na pump isozymes during evolution and their tissue-specific and developmental pattern of expression suggests that the different Na-K-ATPases have evolved distinct properties to respond to cellular requirements. This review focuses on the functional properties, regulation, and possible physiological relevance of the Na pump isozymes. The coexistence of multiple α- and β-isoforms in most cells has hindered the understanding of the roles of the individual polypeptides. The use of heterologous expression systems has helped circumvent this problem. The kinetic characteristics of different Na-K-ATPase isozymes to the activating cations (Na + and K + ), the substrate ATP, and the inhibitors Ca 2+ and ouabain demonstrate that each isoform has distinct properties. In addition, intracellular messengers differentially regulate the activity of the individual Na-K-ATPase isozymes. Thus the regulation of specific Na pump isozymes gives cells the ability to precisely coordinate Na-K-ATPase activity to their physiological requirements. ouabain sodium pump protein kinases Footnotes Address for reprint requests: G. Blanco, Dept. of Cell Biology and Physiology, Washington Univ. School of Medicine, 660 S. Euclid Ave., St. Louis, MO 63110. Copyright © 1998 the American Physiological Society

Journal

AJP - Renal PhysiologyThe American Physiological Society

Published: Nov 1, 1998

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