Mammalian tRNA genes: nucleotide sequence of rat genes for tRNAAsp, tRNAGly and tRNAGlu.

A cloned 2.1 kb fragment of rat DNA hybridized to purified tRNAAsp has been sequenced. The result revealed that in addition to the putative gene for tRNAAspGAU(C), the fragment contained the tRNAGlyGGA(G) and tRNAGluGAG genes. The genes for tRNAAsp, tRNAGly and tRNAGlu have the same polarity, are arranged in this order and are regularly separated by DNA regions of about 450 bp. These rat genes contain neither intervening sequences nor the CCA sequence expected in the 3'-end of the mature tRNA. As observed in lower eukaryotic tRNA genes, the 5'-flanking regions of the three rat genes do not have any significant sequence homology as a regulatory element. In the 3'-flanking region, the sequences CTTTTTG and CTTTTG are present 11 bp downstream from the 3'-end of the genes for tRNAAsp and tRNAGly, respectively. The same CTTTTG sequence is repeated twice in regions 47 and 60 bp away from the tRNAGlu gene. The short T cluster common to the three genes might be the transcription termination site as in lower eukaryotic tRNA genes.