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Table 1 Equivalences between alphabet symbols and nucleotides

From: A method for automatically extracting infectious disease-related primers and probes from the literature

Alphabet Symbol Permissible Nucleotides Complement Meaning
A A T [A]denine
B C | G | T V Any but Adenine
C C G [C]ytosine
D A | G | T H Any but Cytosine
G G C [G]uanine
H A | C | T D Any but Guanine
K G | T M [K]eto
M A | C K A[M]ino
N A | C | G | T N A[N]y nucleotide
R A | G Y Pu[R]ine
S C | G S [S]trong (3 H-bonds)
T T A [T]hymine
V A | C | G B Any but Thymine
W A | T W [W]eak (2 H-bonds)
Y C | T R P[Y]rimidine
  1. This table (adapted from shows the mappings between wildcard symbols used to represent DNA sequences in scientific papers and their permissible nucleotide types.