Table 1.

The genetic code: anticodons

5′	A		G		U		C		3′
A	AAA	Phe	AGA	Ser	AUA	Tyr	ACA	Cys
G	GAA	Phe	GGA	Ser	GUA	Tyr	GCA	Cys	A
U	UAA	Leu	UGA	Ser	UUA	Stop	UCA	Stop
C	CAA	Leu	CGA	Ser	CUA	Stop	CCA	Trp
A	AAG	Leu	AGG	Pro	AUG	His	ACG	Arg
G	GAG	Leu	GGG	Pro	GUG	His	GCG	Arg	G
U	UAG	Leu	UGG	Pro	UUG	Gln	UCG	Arg
C	CAG	Leu	CGG	Pro	CUG	Gln	CCG	Arg
A	AAU	Ile	AGU	Thr	AUU	Asn	ACU	Ser
G	GAU	Ile	GGU	Thr	GUU	Asn	GCU	Ser	U
U	UAU	Ile	UGU	Thr	UUU	Lys	UCU	Arg
C	CAU	Met	CGU	Thr	CUU	Lys	CCU	Arg
A	AAC	Val	AGC	Ala	AUC	Asp	ACC	Gly
G	GAC	Val	GGC	Ala	GUC	Asp	GCC	Gly	C
U	UAC	Val	UGC	Ala	UUC	Glu	UCC	Gly
C	CAC	Val	CGC	Ala	CUC	Glu	CCC	Gly
		G2-C71				C2-G71

Boxed areas are amino acids activated by class I aaRSs, and shaded areas are those activated by class II aaRSs. The vertical line divides the table into two halves in accordance with the consensus second base pair (shown below) in the acceptor helix of corresponding tRNAs when they are recognized by the opposite aaRSs (see text and Fig. 1 for detail).