Separation of the structural requirements for agonist-promoted activation and sequestration of the beta-adrenergic receptor.

The deletion of residues 222-229 from the hamster beta 2-adrenergic receptor (beta AR) resulted in an inability of the mutant receptor to couple to the guanine nucleotide-binding protein (G protein) Gs and to undergo the agonist-mediated sequestration response that is associated with desensitization [Mol. Pharmacol. 34:132-138 (1989)]. Replacement of this region of the beta AR with the analogous region of the M1-muscarinic acetylcholine receptor restored the sequestration response but not the G protein activation. These data suggest that there is a structural, rather than a functional, relationship between these two processes and demonstrate that G protein coupling is not a prerequisite for receptor sequestration.