Defay R E, Astruc M E, Roussillon S, Descomps B, Crastes De Paulet A
Biochimie. 1982 May;64(5):331-9. doi: 10.1016/s0300-9084(82)80437-9.
A discriminating system capable of recognizing the oxygenated sterols was investigated in human lymphocytes. After labelling entire cells with 25-hydroxy [3H] cholesterol (10 nM) the cytosol was ultracentrifuged on a linear sucrose density gradient. Bound 25-hydroxy [3H] cholesterol was located in a single peak with a sedimentation coefficient of 8.3 S. Pronase treatment abolished the radioactive peak. This 8.3 S protein had a low binding capacity for 25-hydroxy [3H] cholesterol and probably a high affinity. This last parameter was not determined on account of some difficulties encountered in a cell-free system relating to the physico-chemical properties of 25-hydroxycholesterol. Only the hydroxylated sterols closely related to 25-hydroxycholesterol were capable of specifically binding to the 8.3 S protein, in contrast with cholesterol. This protein differed from the binding proteins of oxygenated derivatives of vitamin D3 and glucocorticoids. With the human lymphocyte as a model and under our experimental conditions, this hydroxylated sterol-binding protein seems to be involved rather in the cell division control than in the regulation of HMG-CoA reductase activity: indeed, the hydroxysterols able to inhibit thymidine [3H] incorporation into DNA are recognized by this protein whereas the hydroxysterols active on HMG-CoA reductase activity without affecting thymidine [3H] incorporation into DNA are not.
在人类淋巴细胞中研究了一种能够识别氧化固醇的鉴别系统。用25-羟基[³H]胆固醇（10 nM）标记整个细胞后，将胞质溶胶在线性蔗糖密度梯度上进行超速离心。结合的25-羟基[³H]胆固醇位于一个沉降系数为8.3 S的单一峰中。链霉蛋白酶处理消除了放射性峰。这种8.3 S的蛋白质对25-羟基[³H]胆固醇的结合能力较低，但亲和力可能较高。由于在无细胞系统中遇到一些与25-羟基胆固醇的物理化学性质相关的困难，最后一个参数未确定。与胆固醇相反，只有与25-羟基胆固醇密切相关的羟基化固醇能够特异性结合到8.3 S的蛋白质上。这种蛋白质不同于维生素D3和糖皮质激素氧化衍生物的结合蛋白。以人类淋巴细胞为模型并在我们的实验条件下，这种羟基化固醇结合蛋白似乎更多地参与细胞分裂控制而非HMG-CoA还原酶活性的调节：实际上，能够抑制[³H]胸苷掺入DNA的羟基固醇可被该蛋白质识别，而对HMG-CoA还原酶活性有活性但不影响[³H]胸苷掺入DNA的羟基固醇则不能被识别。
