Editorial Note on Part 1
Editorial Notes: 1. In Patent and Trademark Office publications and usage the part number is omitted from the numbers of §§ 1.1 to 1.352 and the numbers to the right of the decimal point correspond with the respective rule numbers. 2. For nomenclature changes to part 1, see 68 FR 14335, Mar. 25, 2003; 87 FR 68904, Nov. 17, 2022.

§ 1.821 Nucleotide and/or amino acid sequence disclosures in patent applications. ( a ) Nucleotide and/or amino acid sequences, as used in §§ 1.821 through 1.825, are interpreted to mean an unbranched sequence of 4 or more amino acids or an unbranched sequence of 10 or more nucleotides. Branched sequences are specifically excluded from this definition. Sequences with fewer than four specifically defined nucleotides or amino acids are specifically excluded from this section. “Specifically defined” means those amino acids other than “Xaa” and those nucleotide bases other than “n,” defined in accordance with Appendices A through F to this subpart. Nucleotides and amino acids are further defined as follows: ( 1 ) *Nucleotides.* Nucleotides are intended to embrace only those nucleotides that can be represented using the symbols set forth in Appendix A to this subpart. Modifications (*e.g.,* methylated bases) may be described as set forth in Appendix B to this subpart but shall not be shown explicitly in the nucleotide sequence.
( 2 ) *Amino acids.* Amino acids are those L-amino acids commonly found in naturally occurring proteins and are listed in appendix C to this subpart. Those amino acid sequences containing D-amino acids are not intended to be embraced by this definition. Any amino acid sequence that contains post-translationally modified amino acids may be described as the amino acid sequence that is initially translated using the symbols shown in appendix C to this subpart, with the modified positions (*e.g.,* hydroxylations or glycosylations) being described as set forth in appendix D to this subpart, but these modifications shall not be shown explicitly in the amino acid sequence. Any peptide or protein that can be expressed as a sequence using the symbols in appendix C to this subpart, in conjunction with a description in the Feature section, to describe, for example, modified linkages, cross links and end caps, non-peptidyl bonds, etc., is embraced by this definition. Note 1 to paragraph (a):
Appendices A through F to this subpart contain Tables 1-6 of the World Intellectual Property Organization (WIPO) Handbook on Industrial Property Information and Documentation, Standard ST.25: Standard for the Presentation of Nucleotide and Amino Acid Sequence Listings in Patent Applications (2009).
( b ) Patent applications which contain disclosures of nucleotide and/or amino acid sequences, in accordance with the definition in paragraph (a) of this section, shall, with regard to the manner in which the nucleotide and/or amino acid sequences are presented and described, conform exclusively to the requirements of §§ 1.821 through 1.825.
( c ) Patent applications that contain disclosures of nucleotide and/or amino acid sequences, as defined in paragraph (a) of this section, must contain a “Sequence Listing,” which is a separate part of the specification containing each of those nucleotide and/or amino acid sequences and associated information using the symbols and format in accordance with the requirements of §§ 1.822 and 1.823. The “Sequence Listing” must be submitted as follows, except for a national stage entry under § 1.495(b)(1), where the “Sequence Listing” has been previously communicated by the International Bureau or originally filed in the United States Patent and Trademark Office and complies with Patent Cooperation Treaty (PCT) Rule 5.2: ( 1 ) As an ASCII plain text file, in compliance with § 1.824, submitted via the USPTO patent electronic filing system or on a read-only optical disc under § 1.52(e), accompanied by an incorporation by reference statement of the ASCII plain text file, in a separate paragraph of the specification, in accordance with § 1.77(b)(5);
( 2 ) As a PDF file via the USPTO patent electronic filing system; or
( 3 ) On physical sheets of paper.
( d ) Where the description or claims of a patent application discuss a sequence that is set forth in the “Sequence Listing,” in accordance with paragraph (c) of this section, reference must be made to the sequence by use of a sequence identifier (§ 1.823(a)(5)), preceded by “SEQ ID NO:” or the like, in the text of the description or claims, even if the sequence is also embedded in the text of the description or claims of the patent application. Where a sequence is presented in a drawing, reference must be made to the sequence by use of the sequence identifier (§ 1.823(a)(5)), either in the drawing or in the Brief Description of the Drawings, where the correlation between multiple sequences in the drawing and their sequence identifiers (§ 1.823(a)(5)) in the Brief Description is clear.
( e ) ( 1 ) If the “Sequence Listing” under paragraph (c) of this section is submitted in an application filed under 35 U.S.C. 111(a) as a PDF file (§ 1.821(c)(2)) via the USPTO patent electronic filing system or on physical sheets of paper (§ 1.821(c)(3)), then the following must be submitted: ( i ) A CRF of the “Sequence Listing,” in accordance with the requirements of § 1.824; and
( ii ) A statement that the sequence information contained in the CRF submitted under paragraph (e)(1)(i) of this section is identical to the sequence information contained in the “Sequence Listing” under paragraph (c) of this section.
( 2 ) If the “Sequence Listing” under paragraph (c) of this section in an application submitted under 35 U.S.C. 371 is a PDF file (paragraph (c)(2) of this section) or on physical sheets of paper (paragraph (c)(3) of this section), and not also as an ASCII plain text file, in compliance with § 1.824 (paragraph (c)(1) of this section), then the following must be submitted: ( i ) A CRF of the “Sequence Listing,” in accordance with the requirements of § 1.824; and
( ii ) A statement that the sequence information contained in the CRF submitted under paragraph (e)(2)(i) of this section is identical to the sequence information contained in the “Sequence Listing” under paragraph (c)(2) or (3) of this section.
( 3 ) If a “Sequence Listing” in ASCII plain text format, in compliance with § 1.824, has not been submitted for an international application under the PCT, and that application contains disclosures of nucleotide and/or amino acid sequences, as defined in paragraph (a) of this section, and is to be searched by the United States International Searching Authority or examined by the United States International Preliminary Examining Authority, then the following must be submitted: ( i ) A CRF of the “Sequence Listing,” in accordance with the requirements of § 1.824;
( ii ) The late furnishing fee for providing a “Sequence Listing” in response to an invitation, as set forth in § 1.445(a)(5); and
( iii ) A statement that the sequence information contained in the CRF, submitted under paragraph (e)(3)(i) of this section, does not go beyond the disclosure in the international application as filed, or a statement that the information recorded in the ASCII plain text file, submitted under paragraph (e)(3)(i) of this section, is identical to the sequence listing contained in the international application as filed, as applicable.
( 4 ) The CRF may not be retained as a part of the patent application file.
( f ) [Reserved]
( g ) If any of the requirements of paragraphs (b) through (e) of this section are not satisfied at the time of filing under 35 U.S.C. 111(a) or at the time of entering the national stage under 35 U.S.C. 371, the applicant will be notified and given a period of time within which to comply with such requirements in order to prevent abandonment of the application. Any amendment to add or replace a “Sequence Listing” and CRF copy thereof in reply to a requirement under this paragraph must be submitted in accordance with the requirements of § 1.825.
( h ) If any of the requirements of paragraph (e)(3) of this section are not satisfied at the time of filing an international application under the PCT, and the application is to be searched by the United States International Searching Authority or examined by the United States International Preliminary Examining Authority, the applicant may be sent a notice necessitating compliance with the requirements within a prescribed time period. Where a “Sequence Listing” under PCT Rule 13*ter* is provided in reply to a requirement under this paragraph, it must be accompanied by a statement that the information recorded in the ASCII plain text file under paragraph (e)(3)(i) of this section is identical to the sequence listing contained in the international application as filed, or does not go beyond the disclosure in the international application as filed, as applicable. It must also be accompanied by the late furnishing fee, as set forth in § 1.445(a)(5). If the applicant fails to timely provide the required CRF, the United States International Searching Authority shall search only to the extent that a meaningful search can be performed without the CRF, and the United States International Preliminary Examining Authority shall examine only to the extent that a meaningful examination can be performed without the CRF.
[63 FR 29634, June 1, 1998, as amended at 65 FR 54680, Sept. 8, 2000; 69 FR 18803, Apr. 9, 2004; 70 FR 10489, Mar. 4, 2005; 86 FR 57048, Oct. 14, 2021]

Editorial Note on Subchapter A of Chapter I
Editorial Note: Part 2 is placed in the separate grouping of parts pertaining to trademarks regulations.

Editorial Note on Subchapter A of Chapter I
Editorial Note: Part 6 is placed in the separate grouping of parts pertaining to trademarks regulations.

Editorial Note on Subchapter A of Chapter I
Editorial Note: Part 7 is placed in the separate grouping of parts pertaining to trademarks regulations.

Editorial Note on Subchapter A of Chapter I
Editorial Note: Part 1 is placed in the separate grouping of parts pertaining to patents regulations.

Editorial Note on Subchapter A of Chapter I
Editorial Note: Part 3 pertaining to both patents and trademarks is placed in the grouping pertaining to patents regulations.

Editorial Note on Subchapter A of Chapter I
Editorial Note: Part 4 is placed in the separate grouping of parts pertaining to patents regulations.

Editorial Note on Subchapter A of Chapter I
Editorial Note: Part 5 is placed in the separate grouping of parts pertaining to patents regulations.