IUPAC codes for nucleotides
(Single-letter codes based on International Union of Pure and Applied Chemistry)The information is gathered from: http://www.iupac.org and http://www.insdc.org/documents/feature_table.html.
| Code | Description | 
|---|---|
| A | Adenine | 
| C | Cytosine | 
| G | Guanine | 
| T | Thymine | 
| U | Uracil | 
| R | Purine (A or G) | 
| Y | Pyrimidine (C, T, or U) | 
| M | C or A | 
| K | T, U, or G | 
| W | T, U, or A | 
| S | C or G | 
| B | C, T, U, or G (not A) | 
| D | A, T, U, or G (not C) | 
| H | A, T, U, or C (not G) | 
| V | A, C, or G (not T, not U) | 
| N | Any base (A, C, G, T, or U) | 
