Radioligand binding studies of the atypical beta 3-adrenergic receptor in rat brown adipose tissue using [3H]CGP 12177.
Two populations of [3H]CGP 12177 binding sites exist in rat interscapular brown adipose tissue (IBAT) plasma membranes. The majority of binding sites are of low affinity with a Kd of 31 nM, a value in close agreement with that for the Kd of [3H]CGP 12177 binding to a cloned rat beta 3-adrenergic receptor (AR) expressed in CHO cells (44 nM). Competition binding studies demonstrate that the Ki values of the cloned rat beta 3-AR and of the low affinity sites in IBAT are 45 and 29 nM, respectively, for BRL 37344 and 1.4 and 1.0 microM, for (-)-propranolol. These findings strongly suggest that the low affinity [3H]CGP 12177 binding site measured in IBAT plasma membranes represents the atypical beta 3-AR in this tissue.
Département de Biochimie médicale, Centre Médical Universitaire, Genève, Switzerland.
P
P
Muzzin
J P
JP
Revelli
C M
CM
Fraser
J P
JP
Giacobino
D002001:Adipose Tissue, Brown / Q000378:metabolism*; D000319:Adrenergic beta-Antagonists / Q000378:metabolism*; D000818:Animals; D001667:Binding, Competitive; D016466:CHO Cells; D006224:Cricetinae; D011412:Propanolamines / Q000378:metabolism*; D011869:Radioligand Assay; D051381:Rats; D011919:Rats, Inbred Strains; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*; D014316:Tritium
D000319:Adrenergic beta-Antagonists; D011412:Propanolamines; D011943:Receptors, Adrenergic, beta; D014316:Tritium; C033394:CGP 12177