Table 1

IUPAC nomenclature for nucleic acids.

Symbol
Meaning
Origin of designation

G
G
Guanine
A
A
Adenine
T
T
Thymine
C
C
Cytosine
R
G or A
puRine
Y
T or C
pYrimidine
M
A or C
aMino
K
G or T
Ketone
S
G or C
Strong interaction (3 H bonds)
W
A or T
Weak interaction (2 H bonds)
H
A or C or T
not-G, H follows G in the alphabet
B
G or T or C
not- A, B follows A
V
G or C or A
not-T (not-U), V follows U
D
G or A or T
not-C, D follows C
N
G or A or T or C
aNy

Aguirre-Hernández et al. BMC Bioinformatics 2007 8:34   doi:10.1186/1471-2105-8-34