Figure 1.
tRNA structure. A, tRNAs fold into an L-shaped three-dimensional structure with extensive intramolecular base-pairing. This tRNAPhe structure (Protein Data Bank code 1OB5) (134) is aminoacylated with phenylalanine (AA). B, in a two-dimensional representation, tRNA resembles a cloverleaf. In both diagrams, the tRNA is colored by structural elements: acceptor stem (red), dihydrouridine (D)-arm (green), anticodon stem (cyan), anticodon (bases 34–36 in purple), variable loop (yellow), TΨC (T) arm (navy), and the conserved CCA-3′ end (white). A schematic mRNA is shown below the tRNA diagram to indicate the tRNA nucleotides that base pair with each codon position.