Wagner T, Gross M, Sigler P B
J Biol Chem. 1984 Apr 25;259(8):4706-9.
Initiator tRNA from yeast (tRNAMeti) was quantitatively misaminoacylated with L-isoleucine using isoleucyl-tRNA synthetase from Escherichia coli. Surprisingly the misaminoacylated Ile-tRNAMeti neither participates in nor inhibits the initiation of globin synthesis in a rabbit reticulocyte lysate, whereas Met-tRNAMeti readily initiates protein synthesis in the same system. The incompetent behavior of Ile-tRNAMeti may be related to the observation that in vitro it does not form a stable complex with eucaryotic initiation factor 2 (eIF-2) and GTP, under conditions which lead to a stable eIF-2 X GTP X Met-tRNAMeti ternary complex. This indicates that eIF-2 can discriminate between the side chains of the aminoacyl adducts of the tRNAMeti during ternary complex formation, the first essential step in initiation of eucaryotic protein synthesis.
使用来自大肠杆菌的异亮氨酰 - tRNA合成酶，酵母起始tRNA（tRNAMeti）被L - 异亮氨酸定量错氨酰化。令人惊讶的是，错氨酰化的Ile - tRNAMeti既不参与也不抑制兔网织红细胞裂解物中珠蛋白合成的起始，而Met - tRNAMeti在同一系统中很容易起始蛋白质合成。Ile - tRNAMeti的无功能行为可能与以下观察结果有关：在体外，在导致形成稳定的eIF - 2·GTP·Met - tRNAMeti三元复合物的条件下，它不会与真核起始因子2（eIF - 2）和GTP形成稳定的复合物。这表明在三元复合物形成过程中，eIF - 2可以在tRNAMeti的氨酰加合物的侧链之间进行区分，这是真核蛋白质合成起始的第一个关键步骤。
