Orci L, Brown M S, Goldstein J L, Garcia-Segura L M, Anderson R G
Cell. 1984 Apr;36(4):835-45. doi: 10.1016/0092-8674(84)90033-3.
The crystalloid endoplasmic reticulum (ER) houses large amounts of HMG CoA reductase, the rate-controlling enzyme in cholesterol synthesis. The crystalloid ER appears in UT-1 cells, a line of Chinese hamster ovary cells that has been chronically starved of cholesterol as a result of growth in the presence of compactin, an inhibitor of reductase. When cholesterol was provided to UT-1 cells in the form of low density lipoprotein (LDL), the reductase and crystalloid ER were destroyed. This destruction was preceded by an increase in the cholesterol content of crystalloid ER membranes, as judged by a 4- to 8-fold increase in their ability to form complexes with filipin, a cholesterol-binding compound that can be visualized in freeze-fracture electron micrographs. Filipin binding to other membranes was unchanged. Thus insertion of cholesterol into the crystalloid ER membrane may trigger the degradation of reductase and the membrane itself.
晶体样内质网（ER）中含有大量的HMG CoA还原酶，这是胆固醇合成中的限速酶。晶体样内质网出现在UT - 1细胞中，UT - 1细胞是中国仓鼠卵巢细胞系，由于在还原酶抑制剂洛伐他汀存在的情况下生长，长期缺乏胆固醇。当以低密度脂蛋白（LDL）的形式向UT - 1细胞提供胆固醇时，还原酶和晶体样内质网会被破坏。在这种破坏之前，晶体样内质网膜的胆固醇含量会增加，这可以通过其与制霉菌素形成复合物的能力增加4至8倍来判断，制霉菌素是一种胆固醇结合化合物，可在冷冻蚀刻电子显微镜下观察到。制霉菌素与其他膜的结合没有变化。因此，胆固醇插入晶体样内质网膜可能会引发还原酶和膜本身的降解。
