Lazard M, Mirande M
Laboratoire d'Enzymologie, Centre National de la Recherche Scientifique, Gif-sur-Yvette, France.
Gene. 1993 Oct 15;132(2):237-45. doi: 10.1016/0378-1119(93)90201-d.
In mammalian cells, the nine aminoacyl-tRNA synthetases (aaRS) specific for the amino acids (aa) Glu, Pro, Ile, Leu, Met, Gln, Lys, Arg and Asp are associated within a multienzyme complex. Arginyl-tRNA synthetase (ArgRS) is characterized by the occurrence of two structurally distinct forms of that enzyme: a complexed (approximately 74 kDa) and a free (approximately 60 kDa) form. The cDNA encoding the 74-kDa species of ArgRS from Chinese hamster ovary cells has been isolated and sequenced. The deduced aa sequence shows 38% identity to the homologous bacterial enzyme but displays an N-terminal polypeptide extension composed of 73 aa, which is absent in the free form of mammalian ArgRS. Two regions of this extension are predicted to be alpha-helical, leading to the clustering of Leu and Ile residues on one side of the helices. This suggests that the N-terminal domain is involved in the assembly of the 74-kDa species of ArgRS within the multisynthetase complex through hydrophobic interactions. By using the isolated cDNA, a Northern blot analysis showed a single mRNA species. Thus, there is a possibility that the free and complexed forms of ArgRS are encoded by the same gene.
在哺乳动物细胞中，负责谷氨酸（Glu）、脯氨酸（Pro）、异亮氨酸（Ile）、亮氨酸（Leu）、甲硫氨酸（Met）、谷氨酰胺（Gln）、赖氨酸（Lys）、精氨酸（Arg）和天冬氨酸（Asp）的9种氨酰-tRNA合成酶（aaRS）存在于一个多酶复合体中。精氨酰-tRNA合成酶（ArgRS）的特点是存在两种结构不同的形式：一种是复合形式（约74 kDa），另一种是游离形式（约60 kDa）。编码中国仓鼠卵巢细胞中74 kDa ArgRS的cDNA已被分离并测序。推导的氨基酸序列与同源细菌酶有38%的同一性，但显示出一个由73个氨基酸组成的N端多肽延伸，这在哺乳动物ArgRS的游离形式中不存在。该延伸的两个区域预计为α螺旋，导致亮氨酸和异亮氨酸残基聚集在螺旋的一侧。这表明N端结构域通过疏水相互作用参与了多合成酶复合体中74 kDa ArgRS的组装。通过使用分离的cDNA进行Northern印迹分析，显示有一个单一的mRNA物种。因此，ArgRS的游离形式和复合形式有可能由同一个基因编码。
