大鼠肝细胞质膜糖皮质激素结合位点的研究

Studies on Glucocorticoid Binding Sites in Plasma Membrane of Rat Uver

分离大鼠肝细胞质膜级分中存在低亲和力的[~3H]皮质酮结合位点。利用LIGAND程序计算该结合的参数为:Kd=4.11±0.57μmol/L,B_(max)=68.87±4.64pmol/mg蛋白。5种甾体取代皮质酮特异性结合的能力依次为:孕酮≈地塞米松>RU26988>RU38486>17β雌二醇。置换实验显示低浓度的RU38486对[~3H]皮质酮的结合无抑制效应,当浓度达到[~3H]皮质酮的100～280倍时,才开始抑制[~3H]皮质酮的结合。

The presence of low-affinity [3H]corticosterone binding sites in plasma membrane isolated from rat liver was determined. The kinetic parameters of this binding estimated by LIGAND program were Kd=4.11±0.57umol/L and Bmax=68.87±4.64pmol/mg protein. The affinities of five steroids for the membrane binding sites in competition with the binding of [3H]corticosterone were of the following or der: progesterones=dexamethasone>RU26988>RU38486>17B^estradiol. Displacement experiments showed that when RU38486 concentration reached 100~280-fold that of [3H]corticosterone, it began to inhibit [3H]corticosterone binding, while low concentration of RU38486 had no inhibitory effect.