mRNA-directed biosynthesis of alpha subunit of thyrotropin: translation in cell-free and whole-cell systems.
mRNA-directed biosynthesis of alpha subunit of thyrotropin: translation in cell-free and whole-cell systems.
复制标题
促甲状腺素α亚基的mRNA指导生物合成：无细胞和全细胞系统中的翻译。
DOI：
10.1073/pnas.76.1.298
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发表时间：
1979
影响因子：
11.1
通讯作者：
B. Weintraub
中科院分区：
文献类型：
--
作者：
I. Kourides;B. Weintraub
在[（35）S]甲硫氨酸存在下，小鼠促甲状腺垂体瘤的mRNA在青蛙卵母细胞（全细胞系统）和小麦胚芽提取物和网织红细胞裂解物（无细胞系统）中翻译。与促甲状腺激素相关的合成肽在三个系统中通过免疫沉淀与亚单位特异性抗血清开发的α亚单位的羊促黄体激素（促黄体激素）和β亚单位的牛促甲状腺激素。在小麦胚芽提取物和网织红细胞裂解物中，合成了促甲状腺素α亚基的单一免疫沉淀形式，通过十二烷基硫酸钠/聚丙烯酰胺凝胶电泳，其表观分子量为14，000。在青蛙卵母细胞中，合成了三种形式的促甲状腺激素免疫沉淀α亚基，表观分子量分别为20，000、14，000和10，000。20，000形式与细胞培养物中未标记的大鼠垂体标准α亚基和（35）S标记的小鼠肿瘤α亚基（20，000 - 21，000）相似;因此，它可能代表了一种过氧化物酶切割和糖基化形式。在所有三个系统中合成的14，000形式可能代表促甲状腺激素的前α亚基;仅在青蛙卵母细胞中合成的10，000形式可能是蛋白水解切割但未糖基化的形式。因为只有促甲状腺素的α亚基被鉴定，并且在任何翻译系统中均未检测到任何一个亚基的更大分子量的免疫沉淀形式，所以促甲状腺素的α和β亚基似乎是从不同的mRNA翻译而来的。
mRNA from mouse thyrotropic pituitary tumors was translated in frog oocytes (a whole-cell system) and in wheat germ extract and reticulocyte lysate (cell-free systems) in the presence of [(35)S]methionine. Synthesized peptides related to thyrotropin were identified in the three systems by immunoprecipitation with subunit-specific antisera developed against the alpha subunit of ovine lutropin (luteinizing hormone) and the beta subunit of bovine thyrotropin. In wheat germ extract and reticulocyte lysate, a single immunoprecipitable form of the alpha subunit of thyrotropin was synthesized with an apparent molecular weight of 14,000 by sodium dodecyl sulfate/polyacrylamide gel electrophoresis. In the frog oocyte, three forms of immunoprecipitable alpha subunit of thyrotropin were synthesized with apparent molecular weights of 20,000, 14,000, and 10,000. The 20,000 form is similar to unlabeled rat pituitary standard alpha subunit and (35)S-labeled mouse tumor alpha subunit in cell cultures (20,000-21,000); thus, it may represent a precursor-cleaved and glycosylated form. The 14,000 form synthesized in all three systems probably represents the pre-alpha subunit of thyrotropin; the 10,000 form, synthesized only in the frog oocyte, could be a proteolytically cleaved but unglycosylated form. Because only the alpha subunit of thyrotropin was identified and no larger molecular weight immunoprecipitable form of either subunit was detected in any of the translation systems, alpha and beta subunits of thyrotropin appear to be translated from separate mRNAs.