Falkensammer G, Fischer-Colbrie R, Richter K, Winkler H
Neuroscience. 1985 Feb;14(2):735-46. doi: 10.1016/0306-4522(85)90323-9.
We have studied the cell-free and cellular synthesis of chromogranins A and B, two immunologically distinct protein families of adrenal chromaffin granules. Two cell-free systems (wheat germ and reticulocyte lysate) were used for translating messenger RNA isolated from bovine adrenal medulla. Two primary translation products could be immunoprecipitated in case of chromogranin A. In the presence of microsomes the two chromogranin A precursors (pre-chromogranins A) were converted into a single protein, apparently by the removal of different signal peptides. For chromogranin B only one precursor (pre-chromogranin B) was translated. In isolated chromaffin cells only one chromogranin A protein was synthesized which corresponded to the processed cell-free translation product. During prolonged incubation this protein became slightly larger and more acidic, probably due to glycosylation in the Golgi region. Chromogranin B is post-translationally converted to a significantly more acidic protein. It is concluded that proteolytic breakdown of newly synthesized chromogranin A and B in chromaffin granules is a slow process comparable to that of the enkephalin precursors. It is not yet known what function these chromogranins have and whether breakdown to smaller subunits is necessary for any function to evolve.
我们研究了嗜铬粒蛋白A和B的无细胞合成及细胞内合成，这是肾上腺嗜铬颗粒中两个免疫特性不同的蛋白质家族。使用两种无细胞系统（小麦胚芽和网织红细胞裂解物）来翻译从牛肾上腺髓质分离的信使核糖核酸。对于嗜铬粒蛋白A，可免疫沉淀出两种初级翻译产物。在微粒体存在的情况下，两种嗜铬粒蛋白A前体（前嗜铬粒蛋白A）显然通过去除不同的信号肽转化为一种单一蛋白质。对于嗜铬粒蛋白B，只翻译出一种前体（前嗜铬粒蛋白B）。在分离的嗜铬细胞中，只合成了一种与经加工的无细胞翻译产物相对应的嗜铬粒蛋白A。在长时间孵育过程中，这种蛋白质变得稍大且酸性更强，可能是由于在高尔基体区域进行了糖基化。嗜铬粒蛋白B在翻译后转化为一种酸性明显更强的蛋白质。得出的结论是，嗜铬颗粒中新合成的嗜铬粒蛋白A和B的蛋白水解降解是一个缓慢的过程，与脑啡肽前体的过程相当。目前尚不清楚这些嗜铬粒蛋白具有什么功能，以及分解为较小亚基对于任何功能的发挥是否必要。
