N-Myristoylation Is Essential for Protein Phosphatases PPM1A and PPM1B to Dephosphorylate Their Physiological Substrates in Cells

Biochem J. 2013 Feb 1;449(3):741-9. doi: 10.1042/BJ20121201.

Abstract

PPM [metal-dependent protein phosphatase, formerly called PP2C (protein phosphatase 2C)] family members play essential roles in regulating a variety of signalling pathways. While searching for protein phosphatase(s) that act on AMPK (AMP-activated protein kinase), we found that PPM1A and PPM1B are N-myristoylated and that this modification is essential for their ability to dephosphorylate the α subunit of AMPK (AMPKα) in cells. N-Myristoylation was also required for two other functions of PPM1A and PPM1B in cells. Although a non-myristoylated mutation (G2A) of PPM1A and PPM1B prevented membrane association, this relocalization did not likely cause the decreased activity towards AMPKα. In in vitro experiments, the G2A mutants exhibited reduced activities towards AMPKα, but much higher specific activity against an artificial substrate, PNPP (p-nitrophenyl phosphate), compared with the wild-type counterparts. Taken together, the results of the present study suggest that N-myristoylation of PPM1A and PPM1B plays a key role in recognition of their physiological substrates in cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • AMP-Activated Protein Kinases / chemistry
  • AMP-Activated Protein Kinases / genetics
  • AMP-Activated Protein Kinases / metabolism
  • Amino Acid Sequence
  • Amino Acid Substitution
  • Animals
  • Base Sequence
  • Catalytic Domain / genetics
  • HEK293 Cells
  • HeLa Cells
  • Humans
  • Mice
  • Models, Molecular
  • Mutagenesis, Site-Directed
  • Myristic Acid / metabolism
  • Nitrophenols / metabolism
  • Organophosphorus Compounds / metabolism
  • Phosphoprotein Phosphatases / chemistry
  • Phosphoprotein Phosphatases / genetics
  • Phosphoprotein Phosphatases / metabolism*
  • Phosphorylation
  • Protein Phosphatase 2C
  • Protein Processing, Post-Translational
  • RNA, Small Interfering / genetics
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Substrate Specificity

Substances

  • Nitrophenols
  • Organophosphorus Compounds
  • RNA, Small Interfering
  • Recombinant Proteins
  • Myristic Acid
  • nitrophenylphosphate
  • AMP-Activated Protein Kinases
  • PPM1A protein, human
  • PPM1B protein, human
  • PPM1G protein, human
  • Phosphoprotein Phosphatases
  • Ppm1a protein, mouse
  • Ppm1b protein, mouse
  • Protein Phosphatase 2C