ADRB2

This gene encodes beta-2-adrenergic receptor which is a member of the G protein-coupled receptor superfamily. This receptor is directly associated with one of its ultimate effectors, the class C L-type calcium channel Ca(V)1.2. This receptor-channel complex also contains a G protein, an adenylyl cyclase, cAMP-dependent kinase, and the counterbalancing phosphatase, PP2A. The assembly of the signaling complex provides a mechanism that ensures specific and rapid signaling by this G protein-coupled receptor. This gene is intronless. Different polymorphic forms, point mutations, and/or downregulation of this gene are associated with nocturnal asthma, obesity and type 2 diabetes. [provided by RefSeq, Jul 2008]

Full Name

Adrenoceptor Beta 2

Function

Beta-adrenergic receptors mediate the catecholamine-induced activation of adenylate cyclase through the action of G proteins. The beta-2-adrenergic receptor binds epinephrine with an approximately 30-fold greater affinity than it does norepinephrine.

Cellular Location

Early endosome; Cell membrane; Golgi apparatus. Colocalizes with VHL at the cell membrane. Activated receptors are internalized into endosomes prior to their degradation in lysosomes. Activated receptors are also detected within the Golgi apparatus.

Topology

Extracellular: 1-34 aa
Helical: 35-58 aa
Cytoplasmic: 59-71 aa
Helical: 72-95 aa
Extracellular: 96-106 aa
Helical: 107-129 aa
Cytoplasmic: 130-150 aa
Helical: 151-174 aa
Extracellular: 175-196 aa
Helical: 197-220 aa
Cytoplasmic: 221-274 aa
Helical: 275-298 aa
Extracellular: 299-305 aa
Helical: 306-329 aa
Cytoplasmic: 330-413 aa

PTM

Palmitoylated. Mainly palmitoylated at Cys-341. Palmitoylation may reduce accessibility of phosphorylation sites by anchoring the receptor to the plasma membrane. Agonist stimulation promotes depalmitoylation and further allows Ser-345 and Ser-346 phosphorylation. Also undergoes transient, ligand-induced palmitoylation at Cys-265 probably by ZDHHC9, ZDHHC14 and ZDHHC18 within the Golgi. Palmitoylation at Cys-265 requires phosphorylation by PKA and receptor internalization and stabilizes the receptor. Could be depalmitoylated by LYPLA1 at the plasma membrane.
Phosphorylated by PKA and BARK upon agonist stimulation, which mediates homologous desensitization of the receptor. PKA-mediated phosphorylation seems to facilitate phosphorylation by BARK.
Phosphorylation of Tyr-141 is induced by insulin and leads to supersensitization of the receptor.
Polyubiquitinated. Agonist-induced ubiquitination leads to sort internalized receptors to the lysosomes for degradation. Deubiquitination by USP20 and USP33, leads to ADRB2 recycling and resensitization after prolonged agonist stimulation. USP20 and USP33 are constitutively associated and are dissociated immediately after agonist stimulation. Ubiquitination by the VHL-E3 ligase complex is oxygen-dependent.
Hydroxylation by EGLN3 occurs only under normoxia and increases the interaction with VHL and the subsequent ubiquitination and degradation of ADRB2.