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Phosphorylation of RGS13 by the cyclic AMP-dependent protein kinase inhibits RGS13 degradation.

Regulators of G-protein signaling (RGS) proteins are scaffolds that control diverse signaling pathways by modulating signalosome formation and by accelerating the GTPase activity of heterotrimeric G proteins. Although expression of many RGS proteins is relatively low in quiescent cells, transcriptional and post-translational responses to environmental cues regulate both their abundance and activity. We found previously that RGS13, one of the smallest RGS proteins in the family, inhibited cyclic AMP-dependent protein kinase (PKA)-induced gene expression through interactions with the transcription factor cAMP-response element-binding (CREB) protein. Here, we show that PKA activation also leads to increased steady-state RGS13 expression through RGS13 phosphorylation, which inhibits RGS13 protein degradation. RGS13 turnover was significantly reduced in cells stimulated with cAMP, which was reversed by expression of the PKA-specific inhibitory peptide PKI. RGS13 phosphorylation was diminished by mutation of an N-terminal Thr residue (T41) identified as a phosphorylation site by mass spectrometry. Mutation of Thr41 in RGS13 to Ala (T41A) reduced steady-state RGS13 levels and its ability to inhibit M2 muscarinic receptor-mediated Erk phosphorylation compared with wild-type RGS13 by attenuating the protective effect of cAMP on RGS13 degradation. RGS13 underwent ubiquitylation, indicating that it is a likely target of the proteasome. These studies are the first to demonstrate post-translational mechanisms controlling the expression of RGS13. Stabilization of RGS13 through PKA-mediated phosphorylation could enhance RGS13 functions, providing negative feedback regulation that promotes cellular desensitization.

Pubmed ID: 20974683


  • Xie Z
  • Yang Z
  • Druey KM


Journal of molecular cell biology

Publication Data

December 24, 2010

Associated Grants

  • Agency: NIAID NIH HHS, Id: AI000939-06

Mesh Terms

  • Amino Acid Substitution
  • Cell Line
  • Cyclic AMP
  • Cyclic AMP-Dependent Protein Kinases
  • Extracellular Signal-Regulated MAP Kinases
  • Humans
  • Mutagenesis, Site-Directed
  • Phosphorylation
  • Proteasome Endopeptidase Complex
  • RGS Proteins
  • Receptor, Muscarinic M2
  • Ubiquitin
  • Ubiquitination