Characterization of a rat tRNA gene cluster: comparison of nucleotide sequences of the gene for tRNALeu newly found in repeating units.

In the rat, DNA carrying a cluster of the genes for tRNAAsp, tRNAGly, and tRNAGlu, aligned in that order, is repeated about 10 times. Seven DNA clones corresponding to the independent repeating units were isolated from a rat gene library. Nucleotide sequence analysis of these clones revealed the presence of a fourth tRNA gene, the gene for tRNALeu, in the cluster. The tRNALeu gene is located about 600 base pairs (bp) upstream from the tRNAAsp gene and its polarity differs from those of the other three tRNA genes. Among the repeating units, the nucleotide sequence of tRNALeu is conserved to a relatively high degree.