Figure 1.

Steps in tRNA processing involving nucleotide deletion or addition for tRNAs encoded by intron-containing and intron-lacking genes. tRNAs are depicted as linear series of circles that are color coded. Purple circles depict transcribed leader and trailer sequences at the 5′ and 3′ ends, respectively; generally, pre-tRNA leader and trailers contain ∼12 nucleotides. Yellow circles depict intron sequences that vary, depending upon the tRNA species, from 14 to 60 nucleotides. Blue and red-colored nucleosides depict the mature exons, where red indicates the anticodon located at nucleotides 34–36. Green circles depict the post-transcriptionally added CCA nucleotides that are required for aminoacylation. G₋₁ added to the 5′ end of tRNA^His is not shown.