title: Mutations that uncouple the beta-adrenergic receptor from Gs and increase agonist affinity.
abstract: The deletion of residues 239-272 from the hamster beta-adrenergic receptor resulted in a loss of the ability of the receptor, expressed in mouse L cells, to stimulate adenylate cyclase (Dixon, R. A. F., Sigal, I. S., Rands, E., Register, R. B., Candelore, M. R., Blake, A. D., and Strader, C. D. (1987) Nature 326, 73-77). This mutant receptor (D(239-272)beta AR) bound the agonist isoproterenol with a single class of binding sites, in contrast to the wild-type beta-adrenergic receptor, which exhibited two classes of agonist affinity sites. We now report that the affinity of D(239-272)beta AR for isoproterenol is relatively insensitive to detergent solubilization or to treatment with either GTP or NaF, indicating the absence of a receptor-Gs interaction. Whereas deletions within the region of amino acids 229-258 did not reduce the ability of the receptor to couple to Gs or to stimulate adenylate cyclase, the deletion of either of the regions 222-229 or 258-270 resulted in receptors which were unable to couple to Gs. The affinities of D(222-229)beta AR, D(239-272)beta AR, and D(258-270)beta AR toward isoproterenol were greater than that observed for the low affinity, uncoupled form of the wild-type receptor. These results suggest a role for the regions of the beta-adrenergic receptor encompassing amino acids 222-229 and 258-270, which are predicted to form amphiphilic helices, in the agonist-promoted activation of Gs.
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism; D000318:Adrenergic beta-Agonists / Q000378:metabolism*; D000818:Animals; D001667:Binding, Competitive; D002872:Chromosome Deletion; D006224:Cricetinae; D019204:GTP-Binding Proteins / Q000378:metabolism*; D020120:Iodocyanopindolol; D007545:Isoproterenol / Q000378:metabolism; D051379:Mice; D010869:Pindolol / Q000031:analogs & derivatives / Q000378:metabolism; D011943:Receptors, Adrenergic, beta / Q000235:genetics* / Q000378:metabolism; D012969:Sodium Fluoride / Q000494:pharmacology; D013329:Structure-Activity Relationship
chemical_list: D000318:Adrenergic beta-Agonists; D011943:Receptors, Adrenergic, beta; D020120:Iodocyanopindolol; D012969:Sodium Fluoride; D010869:Pindolol; D019204:GTP-Binding Proteins; D000262:Adenylyl Cyclases; D007545:Isoproterenol