Protein kinase C-dependent phosphorylation of Na(+)-K(+)-ATPase alpha-subunit in rat kidney cortical tubules

Am J Physiol. 1996 Jul;271(1 Pt 1):C136-43. doi: 10.1152/ajpcell.1996.271.1.C136.


We have previously shown that, in oxygenated rat kidney proximal convoluted tubules (PCT), activation of protein kinase C (PKC) by phorbol 12,13-dibutyrate (PDBu) directly stimulates Na(+)-K(+)-adenosinetriphosphatase (ATPase) activity. PKC modulation of Na(+)-K(+)-ATPase activity by phosphorylation of its alpha-subunit was the postulated mechanism. The present study was therefore designed to investigate the relationship between PKC-mediated phosphorylation of the catalytic alpha-subunit and the cation transport activity of the Na(+)-K(+)-ATPase. In a suspension of rat kidney cortical tubules, activation of PKC by 10(-7) M PDBu increased the level of phosphorylation of the Na(+)-K(+)-ATPase alpha-subunit and stimulated the ouabain-sensitive 86Rb uptake by 47 and 42%, respectively. Time and dose dependence of the PDBu-induced increase in Na(+)-K(+)-ATPase activity and phosphorylation was strongly linearly correlated. The effects of PDBu on phosphorylation and activity of Na(+)-K(+)-ATPase were prevented by GF-109203X, a specific PKC inhibitor, whereas H-89, a specific PKA inhibitor, was ineffective. These results demonstrate that PKC activation induces phosphorylation of the catalytic alpha-subunit of Na(+)-K(+)-ATPase, which may participate in the stimulation of its cation transport activity in the rat PCT.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cyclic AMP-Dependent Protein Kinases / antagonists & inhibitors
  • Enzyme Activation
  • Kidney Cortex
  • Kidney Tubules / metabolism*
  • Male
  • Ouabain / pharmacology
  • Phorbol 12,13-Dibutyrate / pharmacology
  • Phosphorylation / drug effects
  • Precipitin Tests
  • Protein Kinase C / antagonists & inhibitors
  • Protein Kinase C / physiology*
  • Rats
  • Rats, Wistar
  • Sodium-Potassium-Exchanging ATPase / metabolism*


  • Phorbol 12,13-Dibutyrate
  • Ouabain
  • Cyclic AMP-Dependent Protein Kinases
  • Protein Kinase C
  • Sodium-Potassium-Exchanging ATPase