Regulation of elongation factor-2 kinase by pH

Biochemistry. 2002 Nov 12;41(45):13444-50. doi: 10.1021/bi026494p.


Elongation factor-2 kinase (eEF-2K) is a Ca(2+)/calmodulin-dependent protein kinase that phosphorylates and inactivates eEF-2 and that can regulate the rate of protein synthesis at the elongation stage. Here we report that a slight decrease in pH, within the range observed in vivo, leads to a dramatic activation of eEF-2K. The activity of eEF-2K in mouse liver extracts, as well as the activity of purified recombinant human eEF-2K, is low at pH 7.2-7.4 and is increased by severalfold when the pH drops to 6.6-6.8. eEF-2K requires calmodulin for activity at neutral as well as acidic pH. Kinetic studies demonstrate that the pH does not affect the K(M) for ATP or eEF-2 and activation of eEF-2K at acidic pH is due to an increase in V(max). To analyze the potential role of eEF-2K in regulating protein synthesis by pH, we constructed a mouse fibroblast cell line that expresses eEF-2K in a tetracycline-regulated manner. Overexpression of eEF-2K led to a decreased rate of protein synthesis at acidic pH, but not at neutral pH. Our results suggest that pH-dependent activation of eEF-2K may play a role in the global inhibition of protein synthesis during tissue acidosis, which accompanies such processes as hypoxia and ischemia.

Publication types

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

MeSH terms

  • 3T3 Cells
  • Amino Acid Sequence
  • Animals
  • Calcium-Calmodulin-Dependent Protein Kinases / biosynthesis
  • Calcium-Calmodulin-Dependent Protein Kinases / genetics
  • Calcium-Calmodulin-Dependent Protein Kinases / metabolism*
  • Calmodulin / physiology
  • Dictyostelium
  • Elongation Factor 2 Kinase
  • Enzyme Activation / genetics
  • Enzyme Activation / physiology
  • Fibroblasts / enzymology
  • Fibroblasts / metabolism
  • Hydrogen-Ion Concentration
  • Intracellular Fluid / enzymology
  • Intracellular Fluid / physiology*
  • Kinetics
  • Liver / enzymology
  • Liver / metabolism
  • Mice
  • Molecular Sequence Data
  • Peptide Elongation Factor 2 / metabolism
  • Peptide Fragments / chemical synthesis
  • Peptide Fragments / metabolism
  • Phosphorylation
  • Protein Biosynthesis
  • Rabbits
  • Recombinant Fusion Proteins / metabolism
  • Transfection


  • Calmodulin
  • Peptide Elongation Factor 2
  • Peptide Fragments
  • Recombinant Fusion Proteins
  • EEF2K protein, human
  • Calcium-Calmodulin-Dependent Protein Kinases
  • Eef2k protein, mouse
  • Elongation Factor 2 Kinase