The carboxyl terminus of the hamster beta-adrenergic receptor expressed in mouse L cells is not required for receptor sequestration.
The structural basis for agonist-mediated sequestration and desensitization of the beta-adrenergic receptor (beta AR) was examined by oligonucleotide-directed mutagenesis of the hamster beta AR gene and expression of the mutant genes in mouse L cells. Treatment of these cells with the agonist isoproterenol corresponded to a desensitization of beta AR activity. A mutant receptor that bound agonist but did not couple to adenylate cyclase showed a dramatically reduced sequestration response to agonist stimulation. In contrast, beta AR mutants in which the C-terminus was truncated and/or in which two regions that have been proposed as phosphorylation substrates for cAMP-dependent protein kinase were removed showed normal sequestration responses. These results demonstrate that agonist-mediated sequestration of the beta AR can occur in the absence of the C-terminus of the protein and reveal a strong correlation between effective coupling to Gs and sequestration.
D000818:Animals; D000911:Antibodies, Monoclonal; D002451:Cell Compartmentation; D006224:Cricetinae; D000242:Cyclic AMP / Q000502:physiology; D004705:Endocytosis; D005455:Fluorescent Antibody Technique; D019204:GTP-Binding Proteins / Q000378:metabolism; D007545:Isoproterenol / Q000494:pharmacology; D007739:L Cells; D051379:Mice; D009154:Mutation; D011494:Protein Kinases / Q000378:metabolism; D011943:Receptors, Adrenergic, beta / Q000235:genetics / Q000276:immunology / Q000502:physiology*; D011994:Recombinant Proteins / Q000235:genetics; D013329:Structure-Activity Relationship
D000911:Antibodies, Monoclonal; D011943:Receptors, Adrenergic, beta; D011994:Recombinant Proteins; D000242:Cyclic AMP; D011494:Protein Kinases; D019204:GTP-Binding Proteins; D007545:Isoproterenol