Figure 3.

All nucleoside modifications of all 33 synthetic tRNAs that may be sufficient for accurate translation. Outside (shaded): mRNA codons of the genetic code are illustrated in the standard format, except that the 3′ U and C are switched to simplify depiction of decoding. Inside: tRNA nucleotides 34–37 (from 5′ to 3′) and their cognate amino acids. Nucleotides 34–36 are the anticodons, and the 37th nucleotides are represented by black superscripts. Codon and anticodon positions that base pair with each other are colored similarly. Stop codon specificities of release factor (RF) proteins are included. The portions of the tRNA sequences not shown in the figure are unmodified. Expected modifications of in vitro transcripts by the enzymes in Table I, and expected amino-acid and codon specificities are given. ^*=unspecified modification, _=unknown modification status, ms²i⁶A=2-methylthio-N⁶-isopentenyladenosine, m¹G=1-methylguanosine, t6A=N⁶-threonylcarbamoyladenosine, cmnm⁵U=5-carboxymethylaminomethyluridine, V=cmo⁵U=uridine 5-oxyacetic acid, I=inosine, cmnm⁵s²U=5-carboxymethylaminomethyl-2-thiouridine, k2C=lysidine, S=mnm⁵s²U=5-methylaminomethyl-2-thiouridine, mnm⁵U=5-methylaminomethyluridine.