Alpha-2B adrenergic receptor

The alpha-2B adrenergic receptor (α2B adrenoceptor), is a is_associated_with::G-protein coupled receptor. It is a subtype of the is_associated_with::adrenergic receptor family. The human is_associated_with::gene encoding this receptor has the symbol ADRA2B. ADRA2B is_associated_with::orthologs have been identified in several is_associated_with::mammals.

Receptor
α2-adrenergic receptors include 3 highly homologous subtypes: α2A, α2B, and α2C. These receptors have a critical role in regulating is_associated_with::neurotransmitter release from is_associated_with::sympathetic nerves and from adrenergic neurons in the is_associated_with::central nervous system.

Gene
This gene encodes the α2B subtype, which was observed to associate with is_associated_with::eIF-2B, a is_associated_with::guanine nucleotide exchange protein that functions in regulation of translation. A polymorphic variant of the α2B subtype, which lacks 3 is_associated_with::glutamic acids from a glutamic acid is_associated_with::repeat element, was identified to have decreased is_associated_with::G protein-coupled receptor is_associated_with::kinase-mediated phosphorylation and desensitization; this polymorphic form is also associated with reduced is_associated_with::basal metabolic rate in is_associated_with::obese subjects and may therefore contribute to the pathogenesis of obesity. This gene contains no is_associated_with::introns in either its coding or is_associated_with::untranslated sequences.

A deletion variant of the α2B adrenergic receptor has been shown to be related to emotional memory in Europeans and Africans.

In October 2013 researchers from the University of British Columbia confirmed this and further reported that the variant predisposed those people who had it to focus more on negative aspects of a situation. Prof. Rebecca Todd claimed "This is the first study to find that this genetic variation can significantly affect how people see and experience the world.”

Evolution
The ADRA2B gene (sometimes referenced as A2AB) is used in animals as a is_associated_with::nuclear DNA phylogenetic marker. This intronless gene has first been used to explore the phylogeny of the major groups of is_associated_with::mammals, and contributed to reveal that is_associated_with::placental orders are distributed into four major clades: is_associated_with::Xenarthra, is_associated_with::Afrotheria, is_associated_with::Laurasiatheria, and is_associated_with::Euarchontoglires. Comparative analysis of the primary protein sequence of ADRA2B across placentals also showed the high conservation of residues thought to be involved in agonist binding and in G protein–coupling. However, great variations are observed in the very long, third intracellular loop, with a polyglutamyl domain displaying pervasive length differences.

Ligands

 * Agonists
 * (−)-Dibromophakellin


 * Antagonists
 * is_associated_with::Imiloxan
 * is_associated_with::Yohimbine