Trueba M, Vallejo A I, Rodriguez I, Ibarrola I, Sancho M J, Marino A, Macarulla J M
Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias, Universidad del País Vasco/Euskal Herriko Unibertsitatea, Bilbao, Spain.
J Membr Biol. 1989 May;108(2):115-24. doi: 10.1007/BF01871023.
The specific binding of [3H]cortisol to plasma membranes purified from mouse liver, studied by the ultrafiltration method, shows the existence of specific binding sites for cortisol. The kinetic parameters of this binding are KD = 4.4 nM and Bmax = 685 fmol/mg protein in presence of 1 microM of corticosterone. With respect to the binding of 4 nM [3H]cortisol to the membrane, the affinities of the steroids decreased in the following order: deoxycorticosterone greater than corticosterone greater than progesterone greater than cortisol greater than prednisolone greater than testosterone greater than 20 beta-hydroxyprogesterone greater than cortisone. Estradiol, dexamethasone, ouabain and triamcinolone acetonide do not have affinity for this binding site. Neither Ca2+ nor Mg2+ affected the binding of [3H]cortisol to the plasma membranes. Likewise, the presence of agonists and antagonists of alpha and beta-adrenergic receptors did not modify the binding of [3H]cortisol. The results suggest that the plasma membrane binding site characterized is more specific for corticoids and is different from nuclear glucocorticoid and progesterone receptors.
通过超滤法研究了[3H]皮质醇与从小鼠肝脏纯化的质膜的特异性结合，结果表明存在皮质醇的特异性结合位点。在存在1 microM皮质酮的情况下，这种结合的动力学参数为KD = 4.4 nM，Bmax = 685 fmol/mg蛋白质。就4 nM [3H]皮质醇与膜的结合而言，类固醇的亲和力按以下顺序降低：脱氧皮质酮＞皮质酮＞孕酮＞皮质醇＞泼尼松龙＞睾酮＞20β-羟基孕酮＞可的松。雌二醇、地塞米松、哇巴因和曲安奈德对该结合位点没有亲和力。Ca2+和Mg2+均不影响[3H]皮质醇与质膜的结合。同样，α和β肾上腺素能受体的激动剂和拮抗剂的存在也未改变[3H]皮质醇的结合。结果表明，所表征的质膜结合位点对皮质类固醇更具特异性，且不同于核糖皮质激素和孕酮受体。
