Andrés M, Marino A, Macarulla J M, Trueba M
Department of Biochemistry and Molecular Biology, Faculty of Sciences, Basque Country University, Bilbao, Spain.
Cell Mol Life Sci. 1997 Aug;53(8):673-80. doi: 10.1007/s000180050087.
Specific corticosterone binding to calf adrenal cortex plasma membrane was measured using the biologically active radioligand [3H]corticosterone. Corticosterone binding was found to be time-dependent, saturable and reversible, and was reduced by more than 70% when membranes were pretreated with proteases. The population of corticosterone binding sites in calf adrenal cortex plasma membrane was homogeneous and displayed the following characteristics: equilibrium dissociation constant Kd = 77 +/- 8 nM and maximum specific binding capacity Bmax = 70,378 +/- 6,385 fmol/mg protein. The relative affinities of several structural analogues of steroids were deduced from competition assays. From these experiments we can conclude that the plasma membrane binding site characterized is selective for corticosterone and progesterone derivatives, and different from nuclear glucocorticoid, mineralocorticoid, estrogen and progestin receptors. Likewise, this corticosterone binding site is independent of mineralocorticoid and Na+, K(+)-ATPase digitalis receptors. From autoradiographic studies we suggest these corticosterone binding sites are located in the whole adrenal cortex.
使用具有生物活性的放射性配体[3H]皮质酮来测定特异性皮质酮与小牛肾上腺皮质质膜的结合。发现皮质酮结合具有时间依赖性、可饱和性和可逆性，并且当膜用蛋白酶预处理时，结合减少了70%以上。小牛肾上腺皮质质膜中皮质酮结合位点群体是均一的，并表现出以下特征：平衡解离常数Kd = 77 +/- 8 nM，最大特异性结合容量Bmax = 70,378 +/- 6,385 fmol/mg蛋白质。通过竞争试验推断了几种甾体结构类似物的相对亲和力。从这些实验中我们可以得出结论，所表征的质膜结合位点对皮质酮和孕酮衍生物具有选择性，并且不同于核糖皮质激素、盐皮质激素、雌激素和孕激素受体。同样，这个皮质酮结合位点独立于盐皮质激素和Na+、K(+)-ATP酶洋地黄受体。从放射自显影研究中我们认为这些皮质酮结合位点位于整个肾上腺皮质中。
