Winkler M M, Lashbrook C, Hershey J W, Mukherjee A K, Sarkar S
J Biol Chem. 1983 Dec 25;258(24):15141-5.
A cytoplasmic 10 S ribonucleoprotein (iRNP) isolated from chick embryonic muscle is a potent inhibitor of mRNA translation in vitro and contains a 4 S translation inhibitory RNA species (iRNA) (Sarkar, S., Mukherjee, A. K., and Guha, C. (1981) J. Biol. Chem. 256, 5077-5086). Using an in vitro assay system, we show that the iRNA has no effect on the elongation phase of peptide synthesis. iRNA inhibits translation at the initiation step by inhibiting mRNA binding to 43 S initiation complexes. The iRNA does not inhibit the binding of Met-tRNAf to the 40 S ribosomal subunit, but rather causes an increase in the level of 43 S initiation complexes in the reticulocyte lysate. The formation of the 80 S initiation complex from the 43 S complex is specifically blocked in the presence of iRNA. The significance of these results in relation to biological function of iRNA is discussed.
从鸡胚肌肉中分离出的一种细胞质10S核糖核蛋白（iRNP）是体外mRNA翻译的有效抑制剂，它含有一种4S翻译抑制性RNA（iRNA）（萨卡尔，S.，慕克吉，A.K.，和古哈，C.（1981年）《生物化学杂志》256，5077 - 5086）。利用体外检测系统，我们发现iRNA对肽链合成的延伸阶段没有影响。iRNA通过抑制mRNA与43S起始复合物的结合在起始步骤抑制翻译。iRNA不抑制甲硫氨酰 - tRNAf与40S核糖体亚基的结合，反而导致网织红细胞裂解物中43S起始复合物水平升高。在iRNA存在的情况下，43S复合物形成80S起始复合物的过程被特异性阻断。讨论了这些结果与iRNA生物学功能的相关性。
