Role of βγ Subunits of G Proteins in Targeting the β-Adrenergic Receptor Kinase to Membrane-Bound Receptors
Abstract
The rate and extent of the agonist-dependent phosphorylation of β_2-adrenergic receptors and rhodopsin by β-adrenergic receptor kinase (β ARK) are markedly enhanced on addition of G protein βγ subunits. With a model peptide substrate it was demonstrated that direct activation of the kinase could not account for this effect. G protein βγ subunits were shown to interact directly with the COOH-terminal region of β ARK, and formation of this βARK-βγ complex resulted in receptor-facilitated membrane localization of the enzyme. The βγ subunits of transducin were less effective at both enhancing the rate of receptor phosphorylation and binding to the COOH-terminus of βARK, suggesting that the enzyme preferentially binds specific βγ complexes. The βγ-mediated membrane localization of βARK serves to intimately link receptor activation to β ARK-mediated desensitization.
- Publication:
-
Science
- Pub Date:
- August 1992
- DOI:
- 10.1126/science.1325672
- Bibcode:
- 1992Sci...257.1264P