The beta 3-adrenergic receptor (ADRB3) is a G-protein coupled receptor encoded by ADRB3 gene and involved in regulation of lipolysis and homeostasis.  It mediates catecholamine-induced activation of adenylate cyclase through the action of G proteins.

The ADRB3 gene is expressed in the small intestine, adipose tissue and vascular endothelium where it is involved in lipolysis, glucose uptake, cardio-inhibition and relaxation of colon, esophagus, and bladder.  An association between ADRB3 gene polymorphisms with obesity, birth weight, growth rate, carcass composition, lamb mortality, and cold survival has been reported.

The ADRB3 gene has been mapped to chromosome 8p11.23.  It comprises of two coding exons and spans approximately 3.9 kb.  Its encoded protein is 408 amino acids in length and weighs about 43kDa.  Polymorphisms in the ADRB3 gene have been received increasing attention because of its potential roles in lipolysis, thermogenesis, and on energy expenditure.  The p.Trp64Arg mutation of ADRB3 is associated with lower resting metabolic rate, abdominal obesity, weight gain, susceptibility to non-insulin-dependent diabetes mellitus (NIDDM), and difficulty in losing weight.