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Mutations of the human beta 2-adrenergic receptor that impair coupling to Gs interfere with receptor down-regulation but not sequestration.

Publication ,  Journal Article
Campbell, PT; Hnatowich, M; O'Dowd, BF; Caron, MG; Lefkowitz, RJ; Hausdorff, WP
Published in: Mol Pharmacol
February 1991

The integrity of coupling of the beta 2-adrenergic receptor (beta 2AR) to its guanine nucleotide-binding protein, Gs, and phosphorylation events on the receptor molecule have been proposed to be important determinants in the processes of receptor sequestration and down-regulation. However, little is known about the molecular mechanisms underlying these processes, and the regions of the receptor molecule that specifically subserve sequestration and down-regulation have yet to be delineated. To address these questions, we stably transfected eight mutant beta 2AR genes into Chinese hamster fibroblasts and evaluated the coupling, sequestration, and down-regulation properties of the mutated receptors. These mutant receptors have been previously demonstrated either to exhibit abnormal coupling to Gs or to lack functionally important phosphorylation sites for either the cAMP-dependent protein kinase or the agonist-dependent beta-adrenergic receptor kinase. All eight mutants exhibited receptor sequestration equivalent in extent to that of the beta 2AR, regardless of their coupling or phosphorylation status. However, four mutants that exhibited various degrees of impairment in coupling to Gs showed blunted receptor down-regulation patterns. Simultaneous treatment with isoproterenol and dibutyryl-cAMP did not improve the abilities of the mutant receptors to undergo down-regulation. These findings demonstrate that a variety of mutant beta 2AR with impaired coupling to Gs are, nevertheless, able to be sequestered normally. In contrast, agonist-induced down-regulation appears to require coupling of the beta 2AR to Gs but is largely independent of the generation of cAMP. Our results also suggest that molecular determinants of the beta 2AR involved in receptor sequestration are distinct from those participating in the down-regulation process.

Duke Scholars

Published In

Mol Pharmacol

ISSN

0026-895X

Publication Date

February 1991

Volume

39

Issue

2

Start / End Page

192 / 198

Location

United States

Related Subject Headings

  • Receptors, Adrenergic, beta
  • Phosphorylation
  • Pharmacology & Pharmacy
  • Mutation
  • Molecular Sequence Data
  • Humans
  • GTP-Binding Proteins
  • Fibroblasts
  • Down-Regulation
  • Cricetulus
 

Citation

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Campbell, P. T., Hnatowich, M., O’Dowd, B. F., Caron, M. G., Lefkowitz, R. J., & Hausdorff, W. P. (1991). Mutations of the human beta 2-adrenergic receptor that impair coupling to Gs interfere with receptor down-regulation but not sequestration. Mol Pharmacol, 39(2), 192–198.
Campbell, P. T., M. Hnatowich, B. F. O’Dowd, M. G. Caron, R. J. Lefkowitz, and W. P. Hausdorff. “Mutations of the human beta 2-adrenergic receptor that impair coupling to Gs interfere with receptor down-regulation but not sequestration.Mol Pharmacol 39, no. 2 (February 1991): 192–98.
Campbell PT, Hnatowich M, O’Dowd BF, Caron MG, Lefkowitz RJ, Hausdorff WP. Mutations of the human beta 2-adrenergic receptor that impair coupling to Gs interfere with receptor down-regulation but not sequestration. Mol Pharmacol. 1991 Feb;39(2):192–8.
Campbell PT, Hnatowich M, O’Dowd BF, Caron MG, Lefkowitz RJ, Hausdorff WP. Mutations of the human beta 2-adrenergic receptor that impair coupling to Gs interfere with receptor down-regulation but not sequestration. Mol Pharmacol. 1991 Feb;39(2):192–198.

Published In

Mol Pharmacol

ISSN

0026-895X

Publication Date

February 1991

Volume

39

Issue

2

Start / End Page

192 / 198

Location

United States

Related Subject Headings

  • Receptors, Adrenergic, beta
  • Phosphorylation
  • Pharmacology & Pharmacy
  • Mutation
  • Molecular Sequence Data
  • Humans
  • GTP-Binding Proteins
  • Fibroblasts
  • Down-Regulation
  • Cricetulus