Beta 2 adrenoceptor (IPR000332)
Short name: ADRB2_rcpt
Overlapping homologous superfamilies
The adrenoceptors (or adrenergic receptors) are rhodopsin-like G protein-coupled receptors that are targets of the catecholamines, especially norepinephrine (noradrenaline) and epinephrine (adrenaline). Many cells possess these receptors, and the binding of a catecholamine to the receptor will generally stimulate the sympathetic nervous system, effect blood pressure, myocardial contractile rate and force, airway reactivity, and a variety of metabolic and central nervous system functions. The clinical uses of adrenergic compounds are vast. Agonists and antagonists interacting with adrenoceptors have proved useful in the treatment of a variety of diseases, including hypertension, angina pectoris, congestive heart failure, asthma, depression, benign prostatic hypertrophy, and glaucoma. These drugs are also useful in several other therapeutic situations including shock, premature labour and opioid withdrawal, and as adjuncts to general anaesthetics.
There are three classes of adrenoceptors, based on their sequence similarity, receptor pharmacology and signalling mechanisms [PMID: 18882199]. These three classes are alpha 1 (a Gq coupled receptor), alpha 2 (a Gi coupled receptor) and beta (a Gs coupled receptor), and each can be further divided into subtypes [PMID: 2855960]. The different subtypes can coexist in some tissues, but one subtype normally predominates.
There are three subtypes of beta adrenoceptors (beta 1-3), the division is mainly based on their affinities to adrenergic agonists and antagonists. All three subtypes act in the main by activating a Gs protein [PMID: 11053129], activating adenylate cyclase activity. The beta 2 subtype also couples to Gi/o protein [PMID: 11053129, PMID: 12063255]. Beta adrenoceptor selective agonists (beta blockers) are used in the treatment of asthma, angina, cardiac conditions and have proven useful in the treatment of migraine, anxiety disorders and hyperthyroidism, and, when applied topically, are useful in the treatment of glaucoma [PMID: 15655528].
This entry represents the beta 2 receptor; it mediates relaxation of smooth muscle including vascular beds, bronchus, intestine and uterus [PMID: 15069206, PMID: 14711933]. Beta 2 adrenoceptors, also mediate glycogenlysis and glucogenesis in the liver [PMID: 1558559], regulate cell metabolism in skeletal muscle [PMID: 18814142] and inhibit the activity of leukocytes and other blood cells. The receptors are found in the heart, where they are involved in increased cardiac output, although to a lesser extent than beta 1 adrenoceptor. The receptors are located presynaptically in nerves, where they facilitate neurotransmitter release, and in the brain, where they regulate a variety of physiological processes [PMID: 11121511].
GO:0004941 beta2-adrenergic receptor activity
GO:0016021 integral component of membrane