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Palmitoylation and its effect on the GTPase-activating activity and conformation of RGS2

Jianqiang Ni1, Liang Qu, Hui Yang

  • 1National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, PR China. nijq@moon.ibp.ac.cn

The International Journal of Biochemistry & Cell Biology
|September 2, 2006
PubMed

Insights

Regulator of G protein signaling 2 (RGS2) protein palmitoylation inhibits its GTPase-activating activity. This modification alters RGS2 conformation, with cysteine 116 being crucial for this effect, impacting G protein signaling regulation.

Area of Science:

  • Molecular Biology
  • Cell Signaling
  • Post-translational Modifications

Background:

  • Regulator of G protein signaling (RGS) proteins modulate G protein-coupled receptor signaling by enhancing GTPase activity.
  • Palmitoylation, a reversible lipid modification, influences protein function and localization in signaling pathways.
  • RGS2 specifically accelerates Gqalpha GTPase activity, but the impact of its palmitoylation remains underexplored.

Purpose of the Study:

  • To investigate the effects of palmitoylation on RGS2 conformation and GTPase-activating protein (GAP) activity.
  • To identify specific palmitoylation sites on RGS2.
  • To elucidate the relationship between palmitoylation-induced conformational changes and RGS2's GAP function.

Main Methods:

  • Site-directed mutagenesis to create cysteine-to-alanine RGS2 mutants.
  • In vitro GTPase assays using a GTPase-deficient Gqalpha mutant.
  • Spectroscopic analysis including intrinsic fluorescence and Circular Dichroism to assess conformational changes.

Main Results:

  • Identified Cys106, Cys116, and Cys199 as key palmitoylation sites on RGS2.
  • Palmitoylation of RGS2 significantly inhibited its GTPase-activating activity towards Gqalpha.
  • Mutation of Cys116 abolished the inhibitory effect of palmitoylation on RGS2's GAP activity.
  • Palmitoylation induced conformational changes in RGS2, evidenced by fluorescence and CD spectroscopy.

Conclusions:

  • Palmitoylation directly impacts RGS2's GTPase-activating function, primarily through alterations in its protein conformation.
  • Cysteine 116 is a critical site for palmitoylation-mediated regulation of RGS2 activity.
  • These findings provide a mechanistic link between RGS2 palmitoylation, conformational dynamics, and G protein signaling modulation.

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