Phosphorylation of Gi protein by cyclic AMP-dependent protein kinase inhibits its dissociation into alpha-subunits and beta gamma-subunits by Mg2+ and GTP gamma S

Eur J Pharmacol. 1991 Jul 12;207(3):189-94. doi: 10.1016/0922-4106(91)90030-l.

Abstract

Pretreatment of partially purified inhibitory GTP-binding protein (Gi, 41 kDa) with activated cyclic AMP-dependent protein kinase (PKA) decreases its ADP-ribosylation by islet-activating protein (pertussis toxin, IAP). We examined whether this decrease was associated with dissociation of the trimer of alpha beta gamma-subunits of Gi protein into alpha-subunits and beta gamma-subunits. Results showed that phosphorylation of the Gi protein by PKA impaired its dissociation into alpha-subunits and beta gamma-subunits by 50 mM Mg2+ and 100 microM GTP gamma S. The results suggested that phosphorylation of the Gi protein by PKA possibly caused a conformational change of the trimer Gi protein.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Diphosphate Ribose / metabolism
  • GTP-Binding Proteins / chemistry
  • GTP-Binding Proteins / metabolism*
  • Guanosine 5'-O-(3-Thiotriphosphate) / pharmacology*
  • Magnesium / pharmacology*
  • NAD / metabolism
  • Pertussis Toxin
  • Phosphorylation
  • Protein Conformation
  • Protein Kinases / metabolism*
  • Virulence Factors, Bordetella / pharmacology

Substances

  • Virulence Factors, Bordetella
  • NAD
  • Adenosine Diphosphate Ribose
  • Guanosine 5'-O-(3-Thiotriphosphate)
  • Pertussis Toxin
  • Protein Kinases
  • GTP-Binding Proteins
  • Magnesium