The insert within lambda Ht363, a recombinant selected from a bank of
human genomic DNA cloned in lambda Ch4A, is described. Southern blot h
ybridization with a mixed tRNA[P-32]pCp probe revealed the presence of
four tRNA genes, which were shown to represent further copies of gene
s previously identified as a solitary tRNA(Gly) gene and as a three ge
ne cluster on two different recombinants. In vitro transcription of a
fragment containing the three gene cluster revealed the presence of a
further pol III gene, which was shown to be that for a tRNA(TCT)(Arg).
This gene contains a 15 bp intron, the presence of which presumably p
re vented its detection on Southern blots by tRNA hybridisation. The g
ene is present in the previously reported cluster and occurs in higher
copy number (>7) in other arrangements in the genome. Most of the cop
ies of the gene have related intron sequences.