The Nucleotide Sequences of Tyrosine Transfer RNAs of Escherichia coli

The tyrosine tRNAs specified by the E. coli amber suppressor gene su III + and the wild type non‐suppressing allele su III − were selectively labelled with 32 P in E. coli infected with transducing phage ψ80 carrying either of these genes. The determination of the nucleotide sequence of the su III + tyrosine tRNA is described. This tRNA has the anticodon CUA. The su III − tRNA differs from su III + tRNA by a single nucleotide and has the anticodon where is a modified guanylic acid residue. E. coli su − cells contain two tyrosine tRNAs (I and II). The determination of the nucleotide sequence of these is described. Species I is identical to su III − tRNA while species II differs by two nucleotides in the variable loop region.