Cell-free translation of the messenger RNA coding for the alpha subunit of thyroid-stimulating hormone.
Cell-free translation of the messenger RNA coding for the alpha subunit of thyroid-stimulating hormone.
复制标题
编码促甲状腺激素 α 亚基的信使 RNA 的无细胞翻译。
DOI：
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发表时间：
1978
影响因子：
4.8
通讯作者：
F. Maloof
中科院分区：
文献类型：
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作者：
W. Chin;J. Habener;J. Kieffer;F. Maloof
从产生促甲状腺激素（TSH）的小鼠垂体肿瘤中制备的聚腺苷化RNA在来源于小麦胚芽、网状细胞和克雷布斯腹水细胞的无膜异种无细胞系统中被翻译。经电泳分析，优势标记产物的表观分子量为14000。这个主要翻译产物的几个色氨酸与从TSH的真实分泌的(Y)亚基中获得的肽相匹配。M = 14000的蛋白是编码TSH (Y)亚基的mRNA翻译的产物。此外，在小麦胚芽系统中还检测到第二种蛋白M = 17000。M, = 14,000和M， = 17,000的翻译产物分别比假定的核心未糖基化(Y （Mr = 10,600）和p (Mr = 13,000) TSH亚基大约3,000至4,000道尔顿，但小于由体外完整肿瘤细胞产生的糖基化TSH-cu亚基se（表观M， = 22,000）和TSH- p（表观M， = 18,000）。研究了镁和钾对小麦胚芽系统中这些蛋白质合成的影响。随着镁浓度的增加（1.7 ~ 3.7 mM）， (Y)产物的数量减少了6倍，而（M = 17000）产物的数量增加了1倍。在低镁浓度[1.7 mM]下，增加钾浓度（40 ~ 115 mM）对M = 14000（1个产物）和M = 17000个产物的相对数量影响不大，但在高镁浓度[3.2 mM]下，对两种产物的合成均有促进作用。结果表明，编码Y亚基的mRNA的翻译产物可能是该亚基的前体形式，其附加序列约为M， = 3,000，与其他蛋白质激素的类似翻译产物中的前体形式相似。TSH的(Y和fl亚基很可能是由
SUMMARY Polyadenylated RNA prepared from a murine pitui- tary tumor that produces thyroid-stimulating hormone (TSH) was translated in membrane-free heterologous cell-free systems derived from wheat germ, reticulo- cytes, and Krebs ascites cells. By electrophoretic anal- yses, the predominant labeled product had an apparent molecular weight (&fr) of 14,000. Several tryptic pep- tides of this major translation product matched those obtained from the authentic, secreted (Y subunit of TSH. The protein of M, = 14,000 is the product of the trans- lation of the mRNA coding for the (Y subunit of TSH. In addition, a second protein of M, = 17,000 was detected in the wheat germ system. Both the M, = 14,000 and M, = 17,000 translation products are larger by approxi- mately 3,000 to 4,000 daltons than are the putative core unglycosylated (Y (Mr = 10,600) and p (Mr = 13,000) subunits of TSH, respectively, but are smaller than those of the glycosylated native TSH-cu subunits se- creted by intact tumor cells in vitro (apparent M, = 22,000) and TSH-P (apparent M, = 18,000). The effects of magnesium and potassium on the synthesis of these proteins in the wheat germ system were examined. Increasing concentrations of magnesium (1.7 to 3.7 mM) resulted in a 6-fold decrease in the amount of (Y product and a a-fold increase in the amount of M, = 17,000 product. Increasing concentrations of potassium (40 to 115 mM) had little effect on the relative amounts of the M, = 14,000 (a product) and M, = 17,000 products at low magnesium concentration [1.7 mM], but stimulated the synthesis of both products at high magnesium concen- tration [3.2 mM]. The results suggest that the product of the translation of the mRNA coding for the (Y subunit is probably a precursor form of the subunit with an additional sequence of approximately M, = 3,000, sim- ilar to the precursor forms found in the analogous translation products for other protein hormones. It is likely that the (Y and fl subunits of TSH are coded for by