Processing of precursor tRNAs in Drosophila. Processing of the 3' end involves an endonucleolytic cleavage and occurs after 5' end maturation.

Transfer RNA biosynthesis is a complex process which includes size trimming and nucleotide modification of an initial tRNA precursor. We have examined the temporal order and the nature of tRNA processing events in a Drosophila in vitro transcription/processing system using Drosophila tRNA genes as templates. RNA sequence analysis of processing products indicates that processing at both 5' and 3' ends occurs by endonucleolytic cleavage. The time course of processing of an initial tRNA precursor to mature tRNA reveals that trimming at the 5' end precedes 3' end maturation.