Identification of the phosphorylation site for cAMP-dependent protein kinase on Na+,K(+)-ATPase and effects of site-directed mutagenesis

J Biol Chem. 1994 Mar 25;269(12):9368-73.


Phosphorylation of purified Na+,K(+)-ATPase by cAMP-dependent protein kinase (protein kinase A) decreases the activity of this enzyme. We have now shown, using several experimental approaches, that a highly conserved seryl residue on the catalytic (alpha) subunit of Na+,K(+)-ATPase, corresponding to Ser943 of the rat alpha 1 isoform, is the phosphorylation site for protein kinase A. cDNAs corresponding to wild-type Na+,K(+)-ATPase and Na+,K(+)-ATPase in which Ser943 was mutated to Ala were transfected into COS cells. Treatment of the transfected cells with forskolin plus 3-isobutyl-1-methylxanthine resulted in a decrease in the activity of the wild-type enzyme but not in that of the mutated enzyme. The results suggest that, in intact cells, the activity of the Na+,K(+)-ATPase is regulated in part by signal transduction pathways that use protein kinase A-dependent phosphorylation of the Na+,K(+)-ATPase alpha subunit.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • 1-Methyl-3-isobutylxanthine / pharmacology
  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Colforsin / pharmacology
  • Cyclic AMP-Dependent Protein Kinases / metabolism*
  • DNA Primers / chemistry
  • Kinetics
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Peptide Mapping
  • Peptides / chemistry
  • Phosphoserine / metabolism
  • Rats
  • Recombinant Proteins
  • Sodium-Potassium-Exchanging ATPase / metabolism*
  • Structure-Activity Relationship


  • DNA Primers
  • Peptides
  • Recombinant Proteins
  • Phosphoserine
  • Colforsin
  • Cyclic AMP-Dependent Protein Kinases
  • Sodium-Potassium-Exchanging ATPase
  • 1-Methyl-3-isobutylxanthine