Specific transcription of eukaryotic tRNA genes in Xenopus germinal vesicle extracts.

Cloned tRNA genes from Drosophila and from yeast have been transcribed faithfully in extracts prepared from Xenopus germinal vesicles. The newly formed RNA is composed of precursor tRNAs (of 5S RNA size) and of tRNAs. The plasmid pCIT12 carries genes for Drosophila tRNALys, tRNAArg, and tRNAAsn, Nucleotide analysis of one RNA species transcribed from pCIT12 DNA showed it to be identical to Drosophila tRNALys; it even contained some of the modified nucleotides expected for this tRNA. This RNA species is formed in the germinal vesicle extract via a larger precursor tRNA molecule that does not contain nucleotide modifications. This simple transcription system should aid studies aimed at defining the regulatory DNA regions responsible for eukaryotic gene transcription. In addition, it may provide tRNA precursors that are needed for detailed investigations of eukaryotic tRNA biosynthesis.