Smirnov A N, Pokrovskaya E V, Kogteva G S, Shevchenko V P, Levina I S, Kulikova L E, Kamernitzky A V
Laboratory of Endocrinology, School of Biology, Lomonosov Moscow State University, Lenin Hills 1/12, Moscow, Russia.
Steroids. 2000 Mar;65(3):163-70. doi: 10.1016/s0039-128x(99)00100-2.
[(3)H]labeled progesterone and a number of its 16alpha, 17alpha-cycloalkano derivatives with an additional three to six-membered D' ring were investigated for mutual competition and equilibrium binding to proteins from rat uterine cytosol. The interaction of all studied [(3)H]ligands with proteins was characterized by comparable affinity (K(d) in nM region) and apparent homogeneity in terms of affinity. At the same time, the concentrations of binding sites for ligands bearing 16alpha,17alpha cyclopentano, cyclohexano, or cyclohexeno substituents were several-fold higher than those for progesterone or 16alpha, 17alpha-cyclopropanoprogesterone. In mutual competition experiments, when [(3)H]progesterone or [(3)H]16alpha, 17alpha-cyclopropanoprogesterone were used, the curves of 'bound radioactivity-log of competitor concentration' for all compounds studied were parallel and corresponded to a model of 'one protein-two ligands.' However, when [(3)H]ligands with bulky 16alpha, 17alpha-substituents (with the possible exception of cyclohexene derivative) were used, competitive curves for various ligands had different appearances and fell into two groups. Parallel curves for derivatives with 5 or 6 carbons in D' ring described by a model of 'one protein-two ligands' formed the 1st group. The 2nd group comprised curves for progesterone or 16alpha, 17alpha-cyclopropanoprogesterone that had lower slopes and could be described by a model of 'two proteins-two ligands.' Taken together, the results suggest the presence in rat uterine cytosol, of a protein in addition to progesterone receptor capable of discriminating between ligands with no or small 16alpha, 17alpha-cycloalkano substituents and ligands with more bulky substituents.
研究了[（3）H]标记的孕酮及其一些具有额外三至六元D'环的16α，17α-环烷衍生物与大鼠子宫胞质溶胶蛋白的相互竞争和平衡结合。所有研究的[（3）H]配体与蛋白质的相互作用的特征在于具有可比的亲和力（K（d）在nM区域）和亲和力方面的明显同质性。同时，带有16α，17α-环戊烷、环己烷或环己烯取代基的配体的结合位点浓度比孕酮或16α，17α-环丙孕酮的结合位点浓度高几倍。在相互竞争实验中，当使用[（3）H]孕酮或[（3）H]16α，17α-环丙孕酮时，所有研究化合物的“结合放射性-竞争者浓度对数”曲线是平行的，并且符合“一种蛋白质-两种配体”模型。然而，当使用具有庞大16α，17α-取代基的[（3）H]配体（环己烯衍生物可能除外）时，各种配体的竞争曲线具有不同的外观，并分为两组。由“一种蛋白质-两种配体”模型描述的D'环中具有5或6个碳原子的衍生物的平行曲线形成第一组。第二组包括孕酮或16α，17α-环丙孕酮的曲线，其斜率较低，可以用“两种蛋白质-两种配体”模型描述。综上所述，结果表明在大鼠子宫胞质溶胶中，除了孕酮受体外，还存在一种蛋白质，该蛋白质能够区分没有或具有小的16α，17α-环烷取代基的配体和具有更庞大取代基的配体。
