A constitutively active mutant beta 2-adrenergic receptor is constitutively desensitized and phosphorylated.

Journal Article

The beta 2-adrenergic receptor (beta 2AR) can be constitutively activated by mutations in the third intracellular loop. Whereas the wild-type receptor exists predominantly in an inactive conformation (R) in the absence of agonist, the mutant receptor appears to spontaneously adopt an active conformation (R*). We now demonstrate that not only is the mutant beta 2AR constitutively active, it is also constitutively desensitized and down-regulated. To assess whether the mutant receptor can constitutively engage a known element of the cellular desensitization machinery, the receptor was purified and reconstituted into phospholipid vesicles. These preparations retained the essential properties of the constitutively active mutant receptor: agonist-independent activity [to stimulate guanine nucleotide-binding protein (Gs)-GTPase] and agonist-specific increase in binding affinity. Moreover, the purified mutant receptor, in the absence of agonist, was phosphorylated by recombinant beta AR-specific kinase (beta ARK) in a fashion comparable to the agonist-occupied wild-type receptor. Thus, the conformation of the mutated receptor is equivalent to the active conformation (R*), which stimulates Gs protein and is identical to the beta ARK substrate.

Full Text

Duke Authors

Cited Authors

  • Pei, G; Samama, P; Lohse, M; Wang, M; Codina, J; Lefkowitz, RJ

Published Date

  • March 29, 1994

Published In

Volume / Issue

  • 91 / 7

Start / End Page

  • 2699 - 2702

PubMed ID

  • 7908440

International Standard Serial Number (ISSN)

  • 0027-8424

Language

  • eng

Conference Location

  • United States