What symbols should be used to represent nucleotide sequences?

According to WIPO Standard ST.26, paragraph 13, all nucleotides in a sequence must be represented using the symbols in Table 1: List of Nucleotides Symbols. Only lowercase letters must be used. The most important symbols are:

• a – for adenine
• c – for cytosine
• g – for guanine
• t – for thymine in DNA or uracil in RNA
• n – for any nucleotide (“a”, “c”, “g”, “t/u”)

The MPEP states: “Any symbol used to represent a nucleotide is the equivalent of only one residue.“

To learn more:

• nucleotide sequences
• DNA
• RNA
• WIPO Standard ST.26
• sequence symbols