| Nucleotide(s) | IUB/GCG1 | Staden2 | Sanger3 | Stanford4 |
| A | A | A | A | A |
| C | C | C | C | C |
| G | G | G | G | G |
| T | T/U | T | T | T/U |
| (AC) | M | 5 | 5 | j |
| (AG) | R | R | R | R |
| (AT) | W | 7 | 7 | L |
| (CG) | S | 8 | 8 | M |
| (CT) | Y | Y | Y | Y |
| (GT) | K | 6 | 6 | K |
| (AGC) | V | - | - | - |
| (ACT) | H | - | - | - |
| (AGT) | H | - | - | - |
| (CGT) | D | - | - | - |
| (AGTC) | X/N | - | X | - |
1Internation Union of Bichemistry convention translates sequences for GENBANK, University of Wisconsin
Genetic Computing Group, EMBL and the National Biomedical Research Foundation.
2The Staden convention is used by the Cambridge University database.
3The Sanger convention is not currently used.
4The Stanford convention is used by the Stanford University database.