The beta adrenergic receptors mediate the effects of endogenous catecholamines, such as epinephrine, by coupling to Gs to stimulate cAMP. Whereas beta1 and beta2 are found predominantly in heart, the beta3 receptor is found primarily in adipose tissue. Activation of adipose beta3 results in lipolysis and thermogenesis. A polymorphism in the human gene for beta3 is associated with weight gain in obese patients. In addition, mice lacking the beta3-adrenoceptor display increased total body fat, particularly on a high fat diet. These observations indicate that beta3 is a possible target for obesity treatments.