CLONING AND CHARACTERIZATION OF CDNA-ENCODING A HUMAN ARGINYL-TRANSFER-RNA SYNTHETASE

Arginyl-tRNA synthetase (ArgRS) plays a key role in protein synthesis as part of a multienzyme complex with a number of other aminoacyl-tRNA synthetase (aaRS) enzymes. We have isolated a full-length cDNA encodi ng ArgRS as part of a project on complementation of radiosensivity in human cells with an Epstein-Barr Virus (EBV) vector-based human cDNA l ibrary. DNA sequence analysis identified an open reading frame of 1983 nucleotides with 87% homology to other mammalian ArgRS genes, The ded uced amino acid (aa) sequence (661 aa) showed 87.7% identity to the Ch inese hamster ovary (CHO) enzyme and 37.7% identity to the homologous Escherichia coli enzyme. Northern blot analysis revealed the presence of a single mRNA species of approx. 2.2 kb. The results described here demonstrate that ArgRS is highly conserved in mammalian cells and con firm the presence of a hydrophobic N-terminal region in the higher-mol ecular-weight complexed form of ArgRS.