(taken in part from the application's abstract) The proposed studies are designed to address the hypothesis that the NH4-terminal segment of the alpha-subunit of the Na-K-ATPase interacts with other cytoplasmic domains of the same subunit to modulate enzyme activity. Site-directed mutagenesis will be used to identify amino acids that are phosphorylated by protein kinase C (PKC); phorbol 12-myristate 13-acetate (PMA) stimulation has been shown to increase the affinity of the enzyme for intracellular Na (sodium), presumably via PKC phosphorylation. Cross-linking reagents will be used to identify cytoplasmic domains that interact with the NH-terminus of the alpha-subunit. The effect of phosphorylation on partial reactions of the Na-K-ATPase will be determined to attempt to define mechanisms of hormonal regulation of the enzyme. The ultimate aim is to understand molecular mechanisms of action of the Na-K-ATPase and thereby define pathophysiology of cardiovascular diseases potentially caused by dysfunction of this critical enzyme.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Small Research Grants (R03)
Project #
5R03DK052273-02
Application #
2518585
Study Section
Special Emphasis Panel (SRC)
Program Officer
Bishop, Terry Rogers
Project Start
1996-09-30
Project End
1999-08-31
Budget Start
1997-09-01
Budget End
1999-08-31
Support Year
2
Fiscal Year
1997
Total Cost
Indirect Cost
Name
University of Houston
Department
Pharmacology
Type
Schools of Pharmacy
DUNS #
800771594
City
Houston
State
TX
Country
United States
Zip Code
77204
Chibalin, A V; Ogimoto, G; Pedemonte, C H et al. (1999) Dopamine-induced endocytosis of Na+,K+-ATPase is initiated by phosphorylation of Ser-18 in the rat alpha subunit and Is responsible for the decreased activity in epithelial cells. J Biol Chem 274:1920-7
Chibalin, A V; Pedemonte, C H; Katz, A I et al. (1998) Phosphorylation of the catalyic alpha-subunit constitutes a triggering signal for Na+,K+-ATPase endocytosis. J Biol Chem 273:8814-9
Pedemonte, C H; Pressley, T A; Cinelli, A R et al. (1997) Stimulation of protein kinase C rapidly reduces intracellular Na+ concentration via activation of the Na+ pump in OK cells. Mol Pharmacol 52:88-97
Pedemonte, C H; Pressley, T A; Lokhandwala, M F et al. (1997) Regulation of Na,K-ATPase transport activity by protein kinase C. J Membr Biol 155:219-27