Nucleotide
Symbol Meaning
A Adenine
C Cytosine
G Guanine
T Thymine
U Uracil
M A or C
R A or G
W A or T
S C or G
Y C or T
K G or T
V A or C or G
H A or C or T
D A or G or T
B C or G or T
X G or A or T or C
N G or A or T or C
Protein
Symbol Meaning
X Any amino acid
B N or D
Z Q or E
Reference
Cornish-Bowden (1985), IUPAC-IUB symbols for nucleotide nomenclature,
Nucl. Acids Res. 13: 3021-3030.