What is the correct format for presenting amino acid symbols in a Sequence Listing?

This page is an FAQ based on guidance from the Manual of Patent Examining Procedure. It is provided as guidance, with links to the ground truth sources. This is information only: it is not legal advice.

According to MPEP 2423.01, the correct format for presenting amino acid symbols in a Sequence Listing is as follows:

• Three-letter symbols for amino acids are required in the Sequence Listing.
• The three-letter symbols must be presented using uppercase for the first character and lowercase for the remaining two characters.

The MPEP states: “In 37 CFR 1.822(b) and 37 CFR 1.822(d), the use of three-letter symbols for amino acids is required in the ‘Sequence Listing’. The three-letter symbols must be presented using the upper case for the first character and lower case for the remaining two characters.”

Additionally, the MPEP encourages the use of three-letter symbols throughout the entire disclosure for easier readability: “Applicants are encouraged to use the three-letter symbols for amino acids throughout the disclosure, instead of the one-letter symbols, for easier reading of the application and any patent issuing therefrom.”