Expanded Letter Code
In addition to the conventional GATC symbols, there is an expanded letter code to indicate a position within a sequence that may be flexible when defining sequences.
| Letter | Nucleotide(s) included |
|---|---|
| A | A |
| T | T |
| G | G |
| C | C |
| R | G or A |
| Y | T or C |
| M | A or C |
| K | G or T |
| S | G or C |
| W | A or T |
| H | A or C or T |
| B | G or T or C |
| V | G or C or A |
| D | G or T or A |
| N | G or T or A or C |
For example, if the sequences known to bind protein X are known to be AAAAAAGAAA, AAAAAACAAA, AAAAAATAAA, and AAAAAAAAAA, this can be expressed as AAAAAANAAA.
Read more about this topic: Nucleic Acid Nomenclature
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