Porto C S, Musto N A, Bardin C W, Gunsalus G L
Population Council, New York, NY 10021.
Endocrinology. 1992 May;130(5):2931-6. doi: 10.1210/endo.130.5.1315262.
Studies of MCF-7 breast cancer cells demonstrated that sex hormone-binding globulin (SHBG) is internalized by receptor-mediated endocytosis. The present study demonstrated specific binding of SHBG to receptor on membranes isolated from MCF-7 cells. Scatchard analysis of these binding studies suggested that SHBG binds to a single class of sites on membranes. The analysis yielded a dissociation constant (Kd) at 37 C of 3 x 10(-8) M and a binding capacity of 48 +2- 0.12 pmol/mg protein. A procedure for solubilizing the SHBG receptor from MCF-7 membranes used buffers containing protease inhibitors, 10% glycerol, and 10 mM 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate. Solubilization of the receptor resulted in a 5-fold increase in its binding capacity (246 +/- 14 pmol/mg protein) and a 10-fold decrease in binding affinity (Kd at 37 C = 2 x 10(-7) M).
对MCF - 7乳腺癌细胞的研究表明，性激素结合球蛋白（SHBG）通过受体介导的内吞作用被内化。本研究证明了SHBG与从MCF - 7细胞分离的膜上的受体特异性结合。对这些结合研究的斯卡查德分析表明，SHBG与膜上的一类位点结合。分析得出在37℃时的解离常数（Kd）为3×10⁻⁸M，结合容量为48±2 - 0.12 pmol/mg蛋白质。一种从MCF - 7膜中溶解SHBG受体的方法使用了含有蛋白酶抑制剂、10%甘油和10 mM 3 - [(3 - 胆酰胺丙基)二甲基铵] - 1 - 丙烷磺酸盐的缓冲液。受体的溶解导致其结合容量增加了5倍（246±14 pmol/mg蛋白质），结合亲和力降低了10倍（37℃时的Kd = 2×10⁻⁷M）。
