ARE 5S RIBOSOMAL-RNA PRIMARY TRANSCRIPTS EDITED

Comparative analysis of the nucleotide sequences of plant 5S rRNA gene s shows numerous discrepancies with the mature 5S rRNAs. Detailed insp ection of these differences revealed that they are mainly due to singl e nucleotide substitutions, insertions and deletions. In several cases also longer insertions were found, two of which are particularly inte resting. Their location in loops resembles tRNA introns. One of these insertions is 79 nucleotides long and can potentially form a tRNA-like structure, with 50% homology to plant tRNA(Gly). This observation led us to propose that, in the maturation of some 5S rDNA transcripts, ed iting and splicing mechanisms may be involved.