IUPAC-IUB SYMBOLS FOR NUCLEOTIDE NOMENCLATURE [Cornish-Bowden (1985) Nucl. Acids Res. 13: 3021-3030.] Symbol Meaning | Symbol Meaning ------------------------------------+--------------------------------- G Guanine | K G or T A Adenine | S G or C C Cytosine | W A or T T Thymine | H A or C or T U Uracil | B G or T or C R Purine (A or G) | V G or C or A Y Pyrimidine (C or T) | D G or T or A M A or C | N G or A or T or C