title: Binding characteristics of glucocorticoid receptor in synaptic plasma membrane from rat brain.
abstract: The study was carried out to identify the specific glucocorticoid membrane binding site (GCMB) on synaptic plasma membrane (SPM), and to investigate the ligand binding properties and physico-chemical characteristics of GCMB. The radioligand binding assay showed that tritiated corticosterone ([3H]B) could bind to GCMB specifically with positive cooperativity. For SPM, the binding capacity (R(zero)) was 46.67 +/- 4.62 fmol/mg protein; the dissociation constant (Kd), 97.48 +/- 18.85 nmol/L, and the Hill coefficient, 1.633 +/- 0.082. Various steroids bound with GCMB in the following rank order: RU26752, aldosterone > corticosterone, cortisol > RU26988, progesterone, R5020, triamcinolone acetonide > testosterone, estradiol > RU38486 > dexamethasone. GCMB, which could be solubilized by detergent Triton X-100, showed thermal stability, although it was susceptible to hydrolysis by trypsin and to the reducing agent, mercaptoethanol. The addition of divalent cations (Ca2+, Mg2+) was beneficial to the ligand binding. The results strongly indicate that GCMB, fulfilling the basic criteria for a receptor, constitutes a novel type of glucocorticoid receptor on neuronal membrane which is significantly different from the cytosolic glucocorticoid receptors.
authors: Department of Physiology, Second Military Medical University, Shanghai, P.R. China.
authors: Z
authors: Z
authors: Guo
authors: Y Z
authors: YZ
authors: Chen
authors: R B
authors: RB
authors: Xu
authors: H
authors: H
authors: Fu
mesh_terms: D000818:Animals; D001921:Brain / Q000502:physiology*; D002118:Calcium / Q000502:physiology; D005260:Female; D005938:Glucocorticoids / Q000493:pharmacokinetics* / Q000502:physiology*; D008274:Magnesium / Q000502:physiology; D008297:Male; D009474:Neurons / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D011965:Receptors, Glucocorticoid / Q000502:physiology*; D013570:Synaptic Membranes / Q000502:physiology*; D009435:Synaptic Transmission / Q000502:physiology*
chemical_list: D005938:Glucocorticoids; D011965:Receptors, Glucocorticoid; D008274:Magnesium; D002118:Calcium