Table 1.
Classification of codon boxes.
| Type of codon box | Codon box | Amino acid | Codon |
|---|---|---|---|
| Type-1 | {aaa} | Lys | AAA |
| {ccc} | Pro | CCC | |
| {ggg} | Gly | GGG | |
| {ttt} | Phe | TTT | |
| Type-2 | {aac} | Gln, Asn, Thr | CAA, AAC, ACA |
| {aag} | Arg, Glu, Lys | AGA, GAA, AAG | |
| {aat} | Ile, Asn | ATA, AAT | |
| {acc} | His, Pro, Thr | CAC, CCA, ACC | |
| {agg} | Arg, Glu, Gly | AGG, GAG, GGA | |
| {att} | Ile, Leu, Tyr | ATT, TTA, TAT | |
| {ccg} | Ala, Arg, Pro | GCC, CGC, CCG | |
| {cct} | Leu, Pro, Ser | CTC, CCT, TCC | |
| {cgg} | Ala, Arg, Gly | GCG, CGG, GGC | |
| {ctt} | Leu, Phe, Ser | CTT, TTC, TCT | |
| {ggt} | Gly, Trp, Val | GGT, TGG, GTG | |
| {gtt} | Cys, Leu, Val | TGT, TTG, GTT | |
| Type-3 | {acg} | Ala, Arg, Asp, Gln, Ser, Thr | GCA, CGA, GAC, CAG, AGC, ACG |
| {act} | His, Ile, Leu, Ser, Thr, Tyr | CAT, ATC, CTA, TCA, ACT, TAC | |
| {agt} | Asp, Met, Ser, Val | GAT, ATG, AGT, GTA | |
| {cgt} | Ala, Arg, Cys, Leu, Ser, Val | GCT, CGT, TGC, CTG, TCG, GTC |
According to the codon box concept, 64 codons can be divided into 20 kinds of codon boxes. Furthermore, the codon boxes can be classified into three categories: Type-1 has only one kind of base; Type-2 has two kinds of bases; and Type-3 has three kinds of bases.