Two nucleotides next to the anticodon of cytoplasmic rat tRNA are likely generated by RNA editing

Abstract

The nucleotide sequences of major cytoplasmic tRNAsp from rat liver and rat ascites hepatoma comprise a U32 and C33 next to the anticodon as was confirmed by different procedures. Additionally we identified a tRNAsp with C32 and U33 in a minor proportion. We have shown earlier that the tRNAASP gene is part of a cluster of tRNAsp genes which is amplified at least ten times in the rat nuclear genome. Six Independent isolated clones display identical sequences in the coding region of the tRNA gene which differ from tRNAMP in having C32 and T33 Using a combination of single-strand conformation polymorphism (SSCP) analyses and direct sequencing of polymerase chain reaction (PCR) products we have now demonstrated that no variant allele of the tRNAAsp gene with T32 and C33 exists in the rat genome. Together with the RNA sequencing data these findings strongly indicate that major rat tRNAAsp is generated by post-transcriptional pyrimidine transitions at positons 32 and 33 and that the minor tRNAsp is its unedited precursor. © 1992 IRL Press at Oxford University Press.