World Intellectual Property Organization

Administrative Instructions under the Patent Cooperation Treaty

Annex C, Appendix 2

Nucleotide and Amino Acid Symbols and Feature Table

Table 1:  List of Nucleotides

Symbol Meaning Origin of designation
a a adenine
g g guanine
c c cytosine
t t thymine
u u uracil
r g or a purine
y t/u or c pyrimidine
m a or c amino
k
g or t/u
keto
s g or c strong interactions
3H-bonds
w a or t/u weak interactions
2H-bonds
b g or c
or t/u
not a
d

 

a or g
or t/u
not c
h a or c
or t/u
not g
v a or g
or c
not t, not u
n a or g or c
or t/u, unknown, or other
any

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