Expression of the beta 3-adrenergic receptor in human white adipose tissue.

The results of this study suggest that the atypical beta-adrenergic receptor (beta 3 subtype) is expressed in human white adipose tissue. A beta 3-adrenergic receptor mRNA could be detected in human omental fat poly(A)+ RNA by polymerase chain reaction amplification with appropriate primers. The expression of the beta 3-adrenergic receptor in human fat was confirmed by Northern blot analysis; however, the level of its mRNA was lower than those of the beta 1- and beta 2-adrenergic receptors. Two populations of ((-)-4-(3-t-butylamino-2-hydroxypropoxy)-[5,7-3H]benzimidazole-2-one) ([3H]CGP 12177)-binding sites were identified in human omental fat membranes, one with a high affinity (Kd = 1.7 nM) and the other with a low affinity (Kd = 22 nM). The low affinity binding site population, which should represent the beta 3-adrenergic receptor, was predominant (75% of the total binding sites).