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Structure/function analysis of Na(+)-K(+)-ATPase central isoform-specific region: involvement in PKC regulation
Sandrine V Pierre1, Marie-Josée Duran, Deborah L Carr
1Department of Physiology, Texas Tech University Health Sciences Center, Lubbock, Texas 79430, USA. Sandrine.Pierre@ttuhsc.edu
American Journal of Physiology. Renal Physiology
|October 10, 2002
Summary
The central isoform-specific region (ISR) of Na(+)-K(+)-ATPase alpha-isoforms influences protein function, particularly in response to protein kinase C (PKC) activation. This structural region does not affect potassium deocclusion patterns.
Area of Science:
- Molecular Biology
- Biochemistry
- Cell Physiology
Background:
- The sodium-potassium ATPase (Na(+)-K(+)-ATPase) is a crucial ion pump with multiple alpha-isoforms.
- Functional diversity among Na(+)-K(+)-ATPase alpha-isoforms is attributed to structural variations, primarily in the N-terminus and a central isoform-specific region (ISR).
- While the N-terminus is a known driver of functional diversity, the role of the central ISR remains less understood.
Purpose of the Study:
- To investigate the contribution of the central isoform-specific region (ISR) of Na(+)-K(+)-ATPase alpha-isoforms to functional variability.
- To determine if the central ISR influences K(+) deocclusion patterns and response to protein kinase C (PKC) activation.
Main Methods:
- Construction of chimeric Na(+)-K(+)-ATPase alpha-isoforms by exchanging the central ISR between rat alpha(1) and alpha(2) isoforms.
- Stable transfection of these chimeric constructs into opossum kidney (OK) cells.
- Characterization of chimeric and full-length isoforms for K(+) deocclusion patterns and response to PKC activation.
Main Results:
- The central ISR of Na(+)-K(+)-ATPase alpha-isoforms plays a role in the response to protein kinase C (PKC) activation.
- Exchange of the central ISR did not significantly alter the K(+) deocclusion pattern of the Na(+)-K(+)-ATPase alpha-isoforms.
- Comparisons between chimeric and full-length isoforms revealed isoform-specific functional contributions of the central ISR.
Conclusions:
- The central isoform-specific region (ISR) of Na(+)-K(+)-ATPase alpha-isoforms contributes to functional diversity, specifically in modulating the response to PKC.
- The central ISR is not the primary determinant of K(+) deocclusion patterns in Na(+)-K(+)-ATPase alpha-isoforms.
- These findings highlight the complex interplay of structural regions in defining the distinct functions of Na(+)-K(+)-ATPase alpha-isoforms.