PROTEIN-SYNTHESIS IN OOCYTES OF XENOPUS-LAEVIS IS NOT REGULATED BY SUPPLY OF MESSENGER-RNA
PROTEIN-SYNTHESIS IN OOCYTES OF XENOPUS-LAEVIS IS NOT REGULATED BY SUPPLY OF MESSENGER-RNA
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DOI：
10.1016/0092-8674(77)90051-4
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发表时间：
1977-01-01
期刊：
影响因子：
64.5
通讯作者：
PARTINGTON, GA
中科院分区：
文献类型：
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作者：
LASKEY, RA;MILLS, AD;PARTINGTON, GA
通过向卵母细胞注射 mRNA 和多聚核糖体，然后用 14C-氨基酸混合物进行标记，研究了 X. laevis 卵母细胞中蛋白质合成的控制。与先前的报道相反，其中注射的卵母细胞用 3H-组氨酸标记，注射的珠蛋白 mRNA 在所有测试浓度下竞争性地减少了氨基酸掺入内源蛋白质。当提供更多 mRNA 时，未检测到总体氨基酸掺入量增加。分别用亮氨酸、蛋氨酸、脯氨酸或缬氨酸标记注射的卵母细胞后，获得了类似的结果。对使用组氨酸作为标签时相互矛盾的结果进行了解释。当注射网织红细胞多核糖体而不是纯化的珠蛋白 mRNA 时，氨基酸掺入内源蛋白中的情况大致保持恒定，并且总体掺入量增加。类似地，当脑心肌炎病毒RNA与球蛋白mRNA或网织红细胞多核糖体一起注射时，球蛋白mRNA导致脑心肌炎蛋白质中的氨基酸掺入减少，但多核糖体却没有这样做。不同类型的 mRNA 显然会竞争严格有限的翻译能力，而这种能力在正常卵母细胞中是饱和的。限制成分存在于多核糖体中并且不是特定于消息的。两栖动物卵母细胞中蛋白质合成的限制不能完全用掩蔽的 mRNA 来解释。
The control of protein synthesis in oocytes of X. laevis was investigated by injecting oocytes with mRNA and polysomes followed by labeling with 14C-amino acid mixtures. Contrary to previous reports in which injected oocytes were labeled with 3H-histidine, injected globin mRNA decreased amino acid incorporation into endogenous proteins competitively at all concentrations tested. No increase in overall amino acid incorporation is detected when more mRNA is supplied. Similar results are obtained after labeling injected oocytes with leucine, methionine, proline or valine individually. An explanation is presented for the conflicting results when histidine is used as a label. When reticulocyte polysomes are injected, rather than purified globin mRNA, incorporation of amino acids into endogenous proteins remains roughly constant and overall incorporation increases. Similarly, when encephalomyocarditis viral RNA is injected together with either globin mRNA or reticulocyte polysomes, the globin mRNA causes decreased amino acid incorporation into encephalomyocarditis proteins, but the polysomes did not do so. Different types of mRNA apparently compete for a strictly limited translational capacity which is saturated in the normal oocyte. The limiting component is present in polysomes and is not message-specific. The constraint on protein synthesis in the amphibian oocyte cannot be fully explained by masked mRNA.