(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.
| 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 |
