The primary structure of six leucine isoacceptor tRNAs of yellow lupin seeds. The structural requirements for amber tRNA suppressor activity.

Six tRNA(Leu) isoacceptors from yellow lupin seeds were purified, sequenced, and their readthrough properties over the UAG stop codon were tested using TMV RNA as a messenger. The tested tRNAs(Leu) did not show amber suppressor activity. The partial structure of tRNA(Gln), a minor species in yellow lupin, was also determined. Comparison of the nucleotide sequence of all known isoacceptors of tRNA(Tyr), tRNA(Gln) and tRNA(Leu) from plants, mammals and ciliates enabled us to find general structural requirements for tRNA to be a UAG suppressor. From the partial sequence of lupin tRNA(Gln) we suggest that it will have readthrough properties.