Kasid A, Laumas K R
Mol Cell Endocrinol. 1980 Aug;19(2):131-42. doi: 10.1016/0303-7207(80)90017-9.
Progestin(norethindrone and norethindrone acetate)-binding protein, exhibiting characteristics similar to uterine progesterone receptor, has been identified in human uterine cytosol. The progestin receptor was characterized by sedimentation coefficient, 4.2 S; Stokes radius, 39 A; frictional ratio, 1.29; isoelectric pH, 4.6; molecular radius, 2.7 nm; and molecular weight in the range 67 000--74 000. The ammonium-sulfate-precipitated progestin-receptor complex was eluted from a DEAE-cellulose column at 0.18 M KCl. The progestin binding was saturable and stereospecific. The sequential variation in receptor concentration (early proliferative, 3800--4300 sites/cell; late proliferative, 9500--11 200 sites/cell; early secretory, 4900--6200 sites/cell; late secretory, 1800--2300 sites/cell) was in conformity for progesterone and the progestins, when concurrently measured. Oral administration of norethindrone significantly reduced the cytoplasmic and nuclear receptor concentration for estradiol and progesterone. A significant observation was that the progestins stabilized the receptor by forming a slowly dissociating complex with a t 1/2 approximately 110--130 min as compared with the progesterone-receptor complex dissociating with t 1/2 approximately 41 min. Thus, the uterine progestin receptor recognizes progestins in general, although with a varying degree of affinity, and the altered rate constants could be of putative importance in determining the biological potency of the progestins.
在人子宫胞质溶胶中已鉴定出与孕激素（炔诺酮和醋酸炔诺酮）结合的蛋白，其表现出与子宫孕酮受体相似的特征。该孕激素受体的特征为沉降系数4.2 S；斯托克斯半径39 Å；摩擦比1.29；等电pH值4.6；分子半径2.7 nm；分子量在67 000至74 000之间。硫酸铵沉淀的孕激素受体复合物在0.18 M KCl浓度下从DEAE - 纤维素柱上洗脱。孕激素结合具有饱和性和立体特异性。当同时测量时，受体浓度的顺序变化（增殖早期，3800 - 4300个位点/细胞；增殖后期，9500 - 11 200个位点/细胞；分泌早期，4900 - 6200个位点/细胞；分泌后期，1800 - 2300个位点/细胞）与孕酮和孕激素相符。口服炔诺酮显著降低了雌二醇和孕酮的细胞质和细胞核受体浓度。一个重要的观察结果是，与半衰期约为41分钟的孕酮 - 受体复合物解离相比，孕激素通过形成半衰期约为110 - 130分钟的缓慢解离复合物来稳定受体。因此，子宫孕激素受体通常能识别孕激素，尽管亲和力程度不同，且改变的速率常数可能在确定孕激素的生物活性方面具有重要意义。
