The β2-adrenoceptor is responsible for relaxation of vascular, uterine, and airway smooth muscle. The β2-adrenoceptor is much less sensitive to noradrenaline then to adrenaline. Many potent and selective β2-adrenoceptor agonists have been developed, which are used in the treatment of asthma. β2-adrenoceptor desensitization, β-arrestin recruitment and internalization are regulated by phosphorylation of carboxyl-terminal serine355/serine356 (pS355/pS356-ß2) and threonine360/serine364 (pT360/pS364-ß2) residues. Agonist-induced phosphorylation of S355/S356 is predominantly mediated by GRK5/6, whereas phosphorylation of T360/S364 is predominantly mediated by GRK2/3. This nomenclature refers to the human β2. For more information on β2-adrenoceptor pharmacology please refer to the IUPHAR database. For further reading refer to:
Nobles KN, Xiao K, Ahn S, Shukla AK, Lam CM, Rajagopal S, Strachan RT, Huang TY, Bressler EA, Hara MR, Shenoy SK, Gygi SP, Lefkowitz RJ. Distinct phosphorylation sites on the β(2)-adrenergic receptor establish a barcode that encodes differential functions of β-arrestin. Sci Signal. 2011 Aug 9;4(185):ra51. doi: 10.1126/scisignal.2001707. PMID: 21868357; PMCID: PMC3415961.
Kobilka BK. Structural insights into adrenergic receptor function and pharmacology. Trends Pharmacol Sci. 2011 Apr;32(4):213-8. doi: 10.1016/j.tips.2011.02.005. Epub 2011 Mar 15. PMID: 21414670; PMCID: PMC3090711.