Methylation of yeast tRNAPhe by enzymes from cytoplasm, chloroplasts and mitochondria of Phaseolus vulgaris.

Pure yeast tRNAPhe was used as a substrate to compare the tRNA methylating activities in Phaseolus vulgaris cytoplasm, chloroplasts and mitochondria, in the presence of S-adenosyl[Me-3H]methionine. The resulting [Me-3H]-tRNAPhe was then analyzed, using the techniques of nucleotide sequence determination. Cytoplasmic and mitochondrial enzymes catalyze the methylation (into m5C) of C48 present in the extra-loop, while chloroplast enzyme preparations catalyze the modification (into m1A) of A14 present in the dihydrouridine loop of tRNAPhe.