Smirnov A N, Pokrovskaya E V, Shevchenko V P, Levina I S, Kamernitzky A V
Laboratory of Endocrinology, School of Biology, Lomonosov Moscow State University, Moscow, 119899, Russia.
Biochemistry (Mosc). 1998 Sep;63(9):1090-7.
Pregna-D'-pentaranes, 16alpha,17alpha-cyclohexanoprogesterone and 6alpha-methyl-16alpha,17alpha-cyclohexanoprogestero ne, were found to specifically interact with the progesterone receptor of soluble fraction from rat uterus. The formation of complexes between 3H-labeled derivatives of these steroids and the protein was complete within 1 to 3 h at 0-4 degreesC. The dissociation of these complexes was a two-phase process, the contribution of the fast dissociating complexes decreasing with increasing preincubation time. The dissociation constant (k-1) values for progesterone, 16alpha, 17alpha-cyclohexanoprogesterone, and 6alpha-methyl-16alpha, 17alpha-cyclohexanoprogesterone complexes with the protein after 1 h preincubation were 6.5 +/- 0.8, 8.8 +/- 5.5, and (16.6 +/- 5.6).10(-4) sec(-1) for the fast phase and 5.1 +/- 0.5, 3.5 +/- 0.8, and (2.8 +/- 0.6).10(-5) sec(-1) for slow phase, respectively. The equilibrium Kd values were 11.7 +/- 2.1, 19.0 +/- 2.0, and 66.1 +/- 14.6 nM for progesterone, 16alpha,17alpha-cyclohexanoprogesterone, and 6alpha-methyl-16alpha,17alpha-cyclohexanoprogestero ne, respectively. The steroids mutually inhibited the binding of their 3H-labeled derivatives to the protein, the inhibition being of competitive type. In the case of [3H]6alpha-methyl-16alpha, 17alpha-cyclohexanoprogesterone, the inhibitory efficacy of progesterone declined with an increase of its concentration; this points to possible heterogeneity of binding sites for the 3H-labeled ligand. The comparison of the results with those obtained by us earlier (Biochemistry (Moscow), 1996, 61, 1034-1041) suggests the existence of significant species differences in progesterone receptor structure within or near the region that interacts with the D-ring of a hormone molecule.
孕甾 - D'-戊环烷、16α,17α - 环己烷孕酮和6α - 甲基 - 16α,17α - 环己烷孕酮被发现能与大鼠子宫可溶性部分的孕酮受体特异性相互作用。这些类固醇的3H标记衍生物与该蛋白质之间复合物的形成在0 - 4℃下1至3小时内完成。这些复合物的解离是一个两相过程，快速解离复合物的贡献随着预孵育时间的增加而减少。预孵育1小时后，孕酮、16α,17α - 环己烷孕酮和6α - 甲基 - 16α,17α - 环己烷孕酮与该蛋白质形成的复合物的解离常数（k - 1）值，快速相分别为6.5±0.8、8.8±5.5和(16.6±5.6)×10⁻⁴秒⁻¹，慢相分别为5.1±0.5、3.5±0.8和(2.8±0.6)×10⁻⁵秒⁻¹。平衡解离常数（Kd）值，孕酮为11.7±2.1 nM，16α,17α - 环己烷孕酮为19.0±2.0 nM，6α - 甲基 - 16α,17α - 环己烷孕酮为66.1±14.6 nM。这些类固醇相互抑制其3H标记衍生物与该蛋白质的结合，这种抑制属于竞争类型。对于[3H]6α - 甲基 - 16α,17α - 环己烷孕酮，孕酮的抑制效力随其浓度增加而下降；这表明3H标记配体的结合位点可能存在异质性。将这些结果与我们之前获得的结果（《生物化学（莫斯科）》，1996年，61卷，1034 - 1041页）进行比较表明，在与激素分子D环相互作用的区域内或附近，孕酮受体结构存在显著的物种差异。
