GBREL.TXT Genetic Sequence Data Bank
February 15 2004
NCBI-GenBank Flat File Release 140.0
Distribution Release Notes
==========================================================================
TABLE OF CONTENTS
==========================================================================
3. FILE FORMATS
3.4 Sequence Entry Files
3.4.1 File Organization
3.4.2 Entry Organization
3.4.3 Sample Sequence Data File
3.4.4 LOCUS Format
3.4.5 DEFINITION Format
3.4.5.1 DEFINITION Format for NLM Entries
3.4.6 ACCESSION Format
3.4.7 VERSION Format
3.4.8 KEYWORDS Format
3.4.9 SEGMENT Format
3.4.10 SOURCE Format
3.4.11 REFERENCE Format
3.4.12 FEATURES Format
3.4.12.1 Feature Key Names
3.4.12.2 Feature Location
3.4.12.3 Feature Qualifiers
3.4.12.4 Cross-Reference Information
3.4.12.5 Feature Table Examples
3.4.13 ORIGIN Format
3.4.14 SEQUENCE Format
==========================================================================
3. FILE FORMATS
3.4 Sequence Entry Files
GenBank releases contain one or more sequence entry data files, one
for each "division" of GenBank.
3.4.1 File Organization
Each of these files has the same format and consists of two parts:
header information (described in section 3.1) and sequence entries for
that division (described in the following sections).
3.4.2 Entry Organization
In the second portion of a sequence entry file (containing the
sequence entries for that division), each record (line) consists of
two parts. The first part is found in positions 1 to 10 and may
contain:
1. A keyword, beginning in column 1 of the record (e.g., REFERENCE is
a keyword).
2. A subkeyword beginning in column 3, with columns 1 and 2 blank
(e.g., AUTHORS is a subkeyword of REFERENCE). Or a subkeyword beginning
in column 4, with columns 1, 2, and 3 blank (e.g., PUBMED is a
subkeyword of REFERENCE).
3. Blank characters, indicating that this record is a continuation of
the information under the keyword or subkeyword above it.
4. A code, beginning in column 6, indicating the nature of an entry
(feature key) in the FEATURES table; these codes are described in
Section 3.4.12.1 below.
5. A number, ending in column 9 of the record. This number occurs in
the portion of the entry describing the actual nucleotide sequence and
designates the numbering of sequence positions.
6. Two slashes (//) in positions 1 and 2, marking the end of an entry.
The second part of each sequence entry record contains the information
appropriate to its keyword, in positions 13 to 80 for keywords and
positions 11 to 80 for the sequence.
The following is a brief description of each entry field. Detailed
information about each field may be found in Sections 3.4.4 to 3.4.14.
LOCUS - A short mnemonic name for the entry, chosen to suggest the
sequence's definition. Mandatory keyword/exactly one record.
DEFINITION - A concise description of the sequence. Mandatory
keyword/one or more records.
ACCESSION - The primary accession number is a unique, unchanging
code assigned to each entry. (Please use this code when citing
information from GenBank.) Mandatory keyword/one or more records.
VERSION - A compound identifier consisting of the primary
accession number and a numeric version number associated with the
current version of the sequence data in the record. This is followed
by an integer key (a "GI") assigned to the sequence by NCBI.
Mandatory keyword/exactly one record.
NID - An alternative method of presenting the NCBI GI
identifier (described above). The NID is obsolete and was removed
from the GenBank flatfile format in December 1999.
KEYWORDS - Short phrases describing gene products and other
information about an entry. Mandatory keyword in all annotated
entries/one or more records.
SEGMENT - Information on the order in which this entry appears in a
series of discontinuous sequences from the same molecule. Optional
keyword (only in segmented entries)/exactly one record.
SOURCE - Common name of the organism or the name most frequently used
in the literature. Mandatory keyword in all annotated entries/one or
more records/includes one subkeyword.
ORGANISM - Formal scientific name of the organism (first line)
and taxonomic classification levels (second and subsequent lines).
Mandatory subkeyword in all annotated entries/two or more records.
REFERENCE - Citations for all articles containing data reported
in this entry. Includes seven subkeywords and may repeat. Mandatory
keyword/one or more records.
AUTHORS - Lists the authors of the citation. Optional
subkeyword/one or more records.
CONSRTM - Lists the collective names of consortiums associated
with the citation (eg, International Human Genome Sequencing Consortium),
rather than individual author names. Optional subkeyword/one or more records.
TITLE - Full title of citation. Optional subkeyword (present
in all but unpublished citations)/one or more records.
JOURNAL - Lists the journal name, volume, year, and page
numbers of the citation. Mandatory subkeyword/one or more records.
MEDLINE - Provides the Medline unique identifier for a
citation. Optional subkeyword/one record.
PUBMED - Provides the PubMed unique identifier for a
citation. Optional subkeyword/one record.
REMARK - Specifies the relevance of a citation to an
entry. Optional subkeyword/one or more records.
COMMENT - Cross-references to other sequence entries, comparisons to
other collections, notes of changes in LOCUS names, and other remarks.
Optional keyword/one or more records/may include blank records.
FEATURES - Table containing information on portions of the
sequence that code for proteins and RNA sequences and information on
experimentally determined sites of biological significance. Optional
keyword/one or more records.
BASE COUNT - Summary of the number of occurrences of each base
code in the sequence. Mandatory keyword/exactly one record.
ORIGIN - Specification of how the first base of the reported sequence
is operationally located within the genome. Where possible, this
includes its location within a larger genetic map. Mandatory
keyword/exactly one record.
- The ORIGIN line is followed by sequence data (multiple records).
// - Entry termination symbol. Mandatory at the end of an
entry/exactly one record.
3.4.3 Sample Sequence Data File
An example of a complete sequence entry file follows. (This example
has only two entries.) Note that in this example, as throughout the
data bank, numbers in square brackets indicate items in the REFERENCE
list. For example, in ACARR58S, [1] refers to the paper by Mackay, et
al.
1 10 20 30 40 50 60 70 79
---------+---------+---------+---------+---------+---------+---------+---------
GBSMP.SEQ Genetic Sequence Data Bank
15 December 1992
GenBank Flat File Release 74.0
Structural RNA Sequences
2 loci, 236 bases, from 2 reported sequences
LOCUS AAURRA 118 bp ss-rRNA RNA 16-JUN-1986
DEFINITION A.auricula-judae (mushroom) 5S ribosomal RNA.
ACCESSION K03160
VERSION K03160.1 GI:173593
KEYWORDS 5S ribosomal RNA; ribosomal RNA.
SOURCE A.auricula-judae (mushroom) ribosomal RNA.
ORGANISM Auricularia auricula-judae
Eukaryota; Fungi; Eumycota; Basidiomycotina; Phragmobasidiomycetes;
Heterobasidiomycetidae; Auriculariales; Auriculariaceae.
REFERENCE 1 (bases 1 to 118)
AUTHORS Huysmans,E., Dams,E., Vandenberghe,A. and De Wachter,R.
TITLE The nucleotide sequences of the 5S rRNAs of four mushrooms and
their use in studying the phylogenetic position of basidiomycetes
among the eukaryotes
JOURNAL Nucleic Acids Res. 11, 2871-2880 (1983)
FEATURES Location/Qualifiers
rRNA 1..118
/note="5S ribosomal RNA"
BASE COUNT 27 a 34 c 34 g 23 t
ORIGIN 5' end of mature rRNA.
1 atccacggcc ataggactct gaaagcactg catcccgtcc gatctgcaaa gttaaccaga
61 gtaccgccca gttagtacca cggtggggga ccacgcggga atcctgggtg ctgtggtt
//
LOCUS ABCRRAA 118 bp ss-rRNA RNA 15-SEP-1990
DEFINITION Acetobacter sp. (strain MB 58) 5S ribosomal RNA, complete sequence.
ACCESSION M34766
VERSION M34766.1 GI:173603
KEYWORDS 5S ribosomal RNA.
SOURCE Acetobacter sp. (strain MB 58) rRNA.
ORGANISM Acetobacter sp.
Prokaryotae; Gracilicutes; Scotobacteria; Aerobic rods and cocci;
Azotobacteraceae.
REFERENCE 1 (bases 1 to 118)
AUTHORS Bulygina,E.S., Galchenko,V.F., Govorukhina,N.I., Netrusov,A.I.,
Nikitin,D.I., Trotsenko,Y.A. and Chumakov,K.M.
TITLE Taxonomic studies of methylotrophic bacteria by 5S ribosomal RNA
sequencing
JOURNAL J. Gen. Microbiol. 136, 441-446 (1990)
FEATURES Location/Qualifiers
rRNA 1..118
/note="5S ribosomal RNA"
BASE COUNT 27 a 40 c 32 g 17 t 2 others
ORIGIN
1 gatctggtgg ccatggcggg agcaaatcag ccgatcccat cccgaactcg gccgtcaaat
61 gccccagcgc ccatgatact ctgcctcaag gcacggaaaa gtcggtcgcc gccagayy
//
---------+---------+---------+---------+---------+---------+---------+---------
1 10 20 30 40 50 60 70 79
Example 9. Sample Sequence Data File
3.4.4 LOCUS Format
The items of information contained in the LOCUS record are always
found in fixed positions. The locus name (or entry name), which is
always sixteen characters or less, begins in position 13. The locus name
is designed to help group entries with similar sequences: the first
three characters usually designate the organism; the fourth and fifth
characters can be used to show other group designations, such as gene
product; for segmented entries the last character is one of a series
of sequential integers.
The number of bases or base pairs in the sequence ends in position 40.
The letters `bp' are in positions 42 to 43. Positions 45 to 47 provide
the number of strands of the sequence. Positions 48 to 53 indicate the
type of molecule sequenced. Topology of the molecule is indicated in
positions 56 to 63.
GenBank sequence entries are divided among many different
'divisions'. Each entry's division is specified by a three-letter code
in positions 65 to 67. See Section 3.3 for an explanation of division
codes.
Positions 69 to 79 of the record contain the date the entry was
entered or underwent any substantial revisions, such as the addition
of newly published data, in the form dd-MMM-yyyy.
The detailed format for the LOCUS line format is as follows:
Positions Contents
--------- --------
01-05 'LOCUS'
06-12 spaces
13-28 Locus name
29-29 space
30-40 Length of sequence, right-justified
41-41 space
42-43 bp
44-44 space
45-47 spaces, ss- (single-stranded), ds- (double-stranded), or
ms- (mixed-stranded)
48-53 NA, DNA, RNA, tRNA (transfer RNA), rRNA (ribosomal RNA),
mRNA (messenger RNA), uRNA (small nuclear RNA), snRNA,
snoRNA. Left justified.
54-55 space
56-63 'linear' followed by two spaces, or 'circular'
64-64 space
65-67 The division code (see Section 3.3)
68-68 space
69-79 Date, in the form dd-MMM-yyyy (e.g., 15-MAR-1991)
Although each of these data values can be found at column-specific
positions, we encourage those who parse the contents of the LOCUS
line to use a token-based approach. This will prevent the need for
software changes if the spacing of the data values ever has to be
modified.
3.4.5 DEFINITION Format
The DEFINITION record gives a brief description of the sequence,
proceeding from general to specific. It starts with the common name of
the source organism, then gives the criteria by which this sequence is
distinguished from the remainder of the source genome, such as the
gene name and what it codes for, or the protein name and mRNA, or some
description of the sequence's function (if the sequence is
non-coding). If the sequence has a coding region, the description may
be followed by a completeness qualifier, such as cds (complete coding
sequence). There is no limit on the number of lines that may be part
of the DEFINITION. The last line must end with a period.
3.4.5.1 DEFINITION Format for NLM Entries
The DEFINITION line for entries derived from journal-scanning at the NLM is
an automatically generated descriptive summary that accompanies each DNA and
protein sequence. It contains information derived from fields in a database
that summarize the most important attributes of the sequence. The DEFINITION
lines are designed to supplement the accession number and the sequence itself
as a means of uniquely and completely specifying DNA and protein sequences. The
following are examples of NLM DEFINITION lines:
NADP-specific isocitrate dehydrogenase [swine, mRNA, 1 gene, 1585 nt]
94 kda fiber cell beaded-filament structural protein [rats, lens, mRNA
Partial, 1 gene, 1873 nt]
inhibin alpha {promoter and exons} [mice, Genomic, 1 gene, 1102 nt, segment
1 of 2]
cefEF, cefG=acetyl coenzyme A:deacetylcephalosporin C o-acetyltransferase
[Acremonium chrysogenum, Genomic, 2 genes, 2639 nt]
myogenic factor 3, qmf3=helix-loop-helix protein [Japanese quails,
embryo, Peptide Partial, 246 aa]
The first part of the definition line contains information describing
the genes and proteins represented by the molecular sequences. This can
be gene locus names, protein names and descriptions that replace or augment
actual names. Gene and gene product are linked by "=". Any special
identifying terms are presented within brackets, such as: {promoter},
{N-terminal}, {EC 2.13.2.4}, {alternatively spliced}, or {3' region}.
The second part of the definition line is delimited by square brackets, '[]',
and provides details about the molecule type and length. The biological
source, i.e., genus and species or common name as cited by the author.
Developmental stage, tissue type and strain are included if available.
The molecule types include: Genomic, mRNA, Peptide. and Other Genomic
Material. Genomic sequences are assumed to be partial sequence unless
"Complete" is specified, whereas mRNA and peptide sequences are assumed
to be complete unless "Partial" is noted.
3.4.6 ACCESSION Format
This field contains a series of six-character and/or eight-character
identifiers called 'accession numbers'. The six-character accession
number format consists of a single uppercase letter, followed by 5 digits.
The eight-character accession number format consists of two uppercase
letters, followed by 6 digits. The 'primary', or first, of the accession
numbers occupies positions 13 to 18 (6-character format) or positions
13 to 20 (8-character format). Subsequent 'secondary' accession numbers
(if present) are separated from the primary, and from each other, by a
single space. In some cases, multiple lines of secondary accession
numbers might be present, starting at position 13.
The primary accession number of a GenBank entry provides a stable identifier
for the biological object that the entry represents. Accessions do not change
when the underlying sequence data or associated features change.
Secondary accession numbers arise for a number of reasons. For example, a
single accession number may initially be assigned to a sequence described in
a publication. If it is later discovered that the sequence must be entered
into the database as multiple entries, each entry would receive a new primary
accession number, and the original accession number would appear as a secondary
accession number on each of the new entries.
3.4.7 VERSION Format
This line contains two types of identifiers for a GenBank database entry:
a compound accession number and an NCBI GI identifier.
LOCUS AF181452 1294 bp DNA PLN 12-OCT-1999
DEFINITION Hordeum vulgare dehydrin (Dhn2) gene, complete cds.
ACCESSION AF181452
VERSION AF181452.1 GI:6017929
^^^^^^^^^^ ^^^^^^^^^^
Compound NCBI GI
Accession Identifier
Number
A compound accession number consists of two parts: a stable, unchanging
primary-accession number portion (see Section 3.4.6 for a description of
accession numbers), and a sequentially increasing numeric version number.
The accession and version numbers are separated by a period. The initial
version number assigned to a new sequence is one. Compound accessions are
often referred to as "Accession.Version" .
An accession number allows one to retrieve the same biological object in the
database, regardless of any changes that are made to the entry over time. But
those changes can include changes to the sequence data itself, which is of
fundamental importance to many database users. So a numeric version number is
associated with the sequence data in every database entry. If an entry (for
example, AF181452) undergoes two sequence changes, its compound accession
number on the VERSION line would start as AF181452.1 . After the first sequence
change this would become: AF181452.2 . And after the second change: AF181452.3 .
The NCBI GI identifier of the VERSION line also serves as a method for
identifying the sequence data that has existed for a database entry over
time. GI identifiers are numeric values of one or more digits. Since they
are integer keys, they are less human-friendly than the Accession.Version
system described above. Returning to our example for AF181452, it was
initially assigned GI 6017929. If the sequence changes, a new integer GI will
be assigned, perhaps 7345003 . And after the second sequence change, perhaps
the GI would become 10456892 .
Why are both these methods for identifying the version of the sequence
associated with a database entry in use? For two reasons:
- Some data sources processed by NCBI for incorporation into its Entrez
sequence retrieval system do not version their own sequences.
- GIs provide a uniform, integer identifier system for every sequence
NCBI has processed. Some products and systems derived from (or reliant
upon) NCBI products and services prefer to use these integer identifiers
because they can all be processed in the same manner.
GenBank Releases contain only the most recent versions of all sequences
in the database. However, older versions can be obtained via GI-based or
Accession.Version-based queries with NCBI's web-Entrez and network-Entrez
applications. A sequence revision history web page is also available:
http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/girevhist
NOTE: All the version numbers for the compound Accession.Version identifier
system were initialized to a value of one in February 1999, when that
system was introduced.
3.4.8 KEYWORDS Format
The KEYWORDS field does not appear in unannotated entries, but is
required in all annotated entries. Keywords are separated by
semicolons; a "keyword" may be a single word or a phrase consisting of
several words. Each line in the keywords field ends in a semicolon;
the last line ends with a period. If no keywords are included in the
entry, the KEYWORDS record contains only a period.
3.4.9 SEGMENT Format
The SEGMENT keyword is used when two (or more) entries of known
relative orientation are separated by a short (<10 kb) stretch of DNA.
It is limited to one line of the form `n of m', where `n' is the
segment number of the current entry and `m' is the total number of
segments.
3.4.10 SOURCE Format
The SOURCE field consists of two parts. The first part is found after
the SOURCE keyword and contains free-format information including an
abbreviated form of the organism name followed by a molecule type;
multiple lines are allowed, but the last line must end with a period.
The second part consists of information found after the ORGANISM
subkeyword. The formal scientific name for the source organism (genus
and species, where appropriate) is found on the same line as ORGANISM.
The records following the ORGANISM line list the taxonomic
classification levels, separated by semicolons and ending with a
period.
3.4.11 REFERENCE Format
The REFERENCE field consists of five parts: the keyword REFERENCE, and
the subkeywords AUTHORS, TITLE (optional), JOURNAL, MEDLINE (optional),
PUBMED (optional), and REMARK (optional).
The REFERENCE line contains the number of the particular reference and
(in parentheses) the range of bases in the sequence entry reported in
this citation. Additional prose notes may also be found within the
parentheses. The numbering of the references does not reflect
publication dates or priorities.
The AUTHORS line lists the authors in the order in which they appear
in the cited article. Last names are separated from initials by a
comma (no space); there is no comma before the final `and'. The list
of authors ends with a period. The TITLE line is an optional field,
although it appears in the majority of entries. It does not appear in
unpublished sequence data entries that have been deposited directly
into the GenBank data bank, the EMBL Nucleotide Sequence Data Library,
or the DNA Data Bank of Japan. The TITLE field does not end with a
period.
The JOURNAL line gives the appropriate literature citation for the
sequence in the entry. The word `Unpublished' will appear after the
JOURNAL subkeyword if the data did not appear in the scientific
literature, but was directly deposited into the data bank. For
published sequences the JOURNAL line gives the Thesis, Journal, or
Book citation, including the year of publication, the specific
citation, or In press.
For Book citations, the JOURNAL line is specially-formatted, and
includes:
editor name(s)
book title
page number(s)
publisher-name/publisher-location
year
For example:
LOCUS AY277550 1440 bp DNA linear BCT 17-JUN-2003
DEFINITION Stenotrophomonas maltophilia strain CSC13-6 16S ribosomal RNA gene,
partial sequence.
ACCESSION AY277550
....
REFERENCE 1 (bases 1 to 1440)
AUTHORS Gonzalez,J.M., Laiz,L. and Saiz-Jimenez,C.
TITLE Classifying bacterial isolates from hypogean environments:
Application of a novel fluorimetric method dor the estimation of
G+C mol% content in microorganisms by thermal denaturation
temperature
JOURNAL (in) Saiz-Jimenez,C. (Ed.);
MOLECULAR BIOLOGY AND CULTURAL HERITAGE: 47-54;
A.A. Balkema, The Netherlands (2003)
The presence of "(in)" signals the fact that the reference is for a book
rather than a journal article. A semi-colon signals the end of the editor
names. The next semi-colon signals the end of the page numbers, and the
colon that immediately *precedes* the page numbers signals the end of the
book title. The publisher name and location are a free-form text string.
Finally, the year appears at the very end of the JOURNAL line, enclosed in
parentheses.
The MEDLINE line provides the National Library of Medicine's Medline
unique identifier for a citation (if known). Medline UIs are 8 digit
numbers.
The PUBMED line provides the PubMed unique identifier for a citation
(if known). PUBMED ids are numeric, and are record identifiers for article
abstracts in the PubMed database :
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed
Citations in PubMed that do not fall within Medline's scope will have only
a PUBMED identifier. Similarly, citations that *are* in Medline's scope but
which have not yet been assigned Medline UIs will have only a PUBMED identifier.
If a citation is present in both the PubMed and Medline databases, both a
MEDLINE and a PUBMED line will be present.
The REMARK line is a textual comment that specifies the relevance
of the citation to the entry.
3.4.12 FEATURES Format
GenBank releases use a feature table format designed jointly by
GenBank, the EMBL Nucleotide Sequence Data Library, and the DNA Data
Bank of Japan. This format is in use by all three databases. The
most complete and accurate Feature Table documentation can be found
on the Web at:
http://www.ncbi.nlm.nih.gov/projects/collab/FT/index.html
Any discrepancy between the abbreviated feature table description
of these release notes and the complete documentation on the Web
should be resolved in favor of the version at the above URL.
The Feature Table specification is also available as a printed
document: `The DDBJ/EMBL/GenBank Feature Table: Definition'. Contact
GenBank at the address shown on the first page of these Release Notes
if you would like a copy.
The feature table contains information about genes and gene products,
as well as regions of biological significance reported in the
sequence. The feature table contains information on regions of the
sequence that code for proteins and RNA sequences. It also enumerates
differences between different reports of the same sequence, and
provides cross-references to other data collections, as described in
more detail below.
The first line of the feature table is a header that includes the
keyword `FEATURES' and the column header `Location/Qualifier.' Each
feature consists of a descriptor line containing a feature key and a
location (see sections below for details). If the location does not
fit on this line, a continuation line may follow. If further
information about the feature is required, one or more lines
containing feature qualifiers may follow the descriptor line.
The feature key begins in column 6 and may be no more than 15
characters in length. The location begins in column 22. Feature
qualifiers begin on subsequent lines at column 22. Location,
qualifier, and continuation lines may extend from column 22 to 80.
Feature tables are required, due to the mandatory presence of the
source feature. The sections below provide a brief introduction to
the feature table format.
3.4.12.1 Feature Key Names
The first column of the feature descriptor line contains the feature
key. It starts at column 6 and can continue to column 20. The list of
valid feature keys is shown below.
Remember, the most definitive documentation for the feature table can
be found at:
http://www.ncbi.nlm.nih.gov/projects/collab/FT/index.html
allele Obsolete; see variation feature key
attenuator Sequence related to transcription termination
C_region Span of the C immunological feature
CAAT_signal `CAAT box' in eukaryotic promoters
CDS Sequence coding for amino acids in protein (includes
stop codon)
conflict Independent sequence determinations differ
D-loop Displacement loop
D_segment Span of the D immunological feature
enhancer Cis-acting enhancer of promoter function
exon Region that codes for part of spliced mRNA
gene Region that defines a functional gene, possibly
including upstream (promotor, enhancer, etc)
and downstream control elements, and for which
a name has been assigned.
GC_signal `GC box' in eukaryotic promoters
iDNA Intervening DNA eliminated by recombination
intron Transcribed region excised by mRNA splicing
J_region Span of the J immunological feature
LTR Long terminal repeat
mat_peptide Mature peptide coding region (does not include stop codon)
misc_binding Miscellaneous binding site
misc_difference Miscellaneous difference feature
misc_feature Region of biological significance that cannot be described
by any other feature
misc_recomb Miscellaneous recombination feature
misc_RNA Miscellaneous transcript feature not defined by other RNA keys
misc_signal Miscellaneous signal
misc_structure Miscellaneous DNA or RNA structure
modified_base The indicated base is a modified nucleotide
mRNA Messenger RNA
mutation Obsolete: see variation feature key
N_region Span of the N immunological feature
old_sequence Presented sequence revises a previous version
polyA_signal Signal for cleavage & polyadenylation
polyA_site Site at which polyadenine is added to mRNA
precursor_RNA Any RNA species that is not yet the mature RNA product
prim_transcript Primary (unprocessed) transcript
primer Primer binding region used with PCR
primer_bind Non-covalent primer binding site
promoter A region involved in transcription initiation
protein_bind Non-covalent protein binding site on DNA or RNA
RBS Ribosome binding site
rep_origin Replication origin for duplex DNA
repeat_region Sequence containing repeated subsequences
repeat_unit One repeated unit of a repeat_region
rRNA Ribosomal RNA
S_region Span of the S immunological feature
satellite Satellite repeated sequence
scRNA Small cytoplasmic RNA
sig_peptide Signal peptide coding region
snRNA Small nuclear RNA
source Biological source of the sequence data represented by
a GenBank record. Mandatory feature, one or more per record.
For organisms that have been incorporated within the
NCBI taxonomy database, an associated /db_xref="taxon:NNNN"
qualifier will be present (where NNNNN is the numeric
identifier assigned to the organism within the NCBI taxonomy
database).
stem_loop Hair-pin loop structure in DNA or RNA
STS Sequence Tagged Site; operationally unique sequence that
identifies the combination of primer spans used in a PCR assay
TATA_signal `TATA box' in eukaryotic promoters
terminator Sequence causing transcription termination
transit_peptide Transit peptide coding region
transposon Transposable element (TN)
tRNA Transfer RNA
unsure Authors are unsure about the sequence in this region
V_region Span of the V immunological feature
variation A related population contains stable mutation
- (hyphen) Placeholder
-10_signal `Pribnow box' in prokaryotic promoters
-35_signal `-35 box' in prokaryotic promoters
3'clip 3'-most region of a precursor transcript removed in processing
3'UTR 3' untranslated region (trailer)
5'clip 5'-most region of a precursor transcript removed in processing
5'UTR 5' untranslated region (leader)
3.4.12.2 Feature Location
The second column of the feature descriptor line designates the
location of the feature in the sequence. The location descriptor
begins at position 22. Several conventions are used to indicate
sequence location.
Base numbers in location descriptors refer to numbering in the entry,
which is not necessarily the same as the numbering scheme used in the
published report. The first base in the presented sequence is numbered
base 1. Sequences are presented in the 5 to 3 direction.
Location descriptors can be one of the following:
1. A single base;
2. A contiguous span of bases;
3. A site between two bases;
4. A single base chosen from a range of bases;
5. A single base chosen from among two or more specified bases;
6. A joining of sequence spans;
7. A reference to an entry other than the one to which the feature
belongs (i.e., a remote entry), followed by a location descriptor
referring to the remote sequence;
A site between two residues, such as an endonuclease cleavage site, is
indicated by listing the two bases separated by a carat (e.g., 23^24).
A single residue chosen from a range of residues is indicated by the
number of the first and last bases in the range separated by a single
period (e.g., 23.79). The symbols < and > indicate that the end point
of the range is beyond the specified base number.
A contiguous span of bases is indicated by the number of the first and
last bases in the range separated by two periods (e.g., 23..79). The
symbols < and > indicate that the end point of the range is beyond the
specified base number. Starting and ending positions can be indicated
by base number or by one of the operators described below.
Operators are prefixes that specify what must be done to the indicated
sequence to locate the feature. The following are the operators
available, along with their most common format and a description.
complement (location): The feature is complementary to the location
indicated. Complementary strands are read 5 to 3.
join (location, location, .. location): The indicated elements should
be placed end to end to form one contiguous sequence.
order (location, location, .. location): The elements are found in the
specified order in the 5 to 3 direction, but nothing is implied about
the rationality of joining them.
3.4.12.3 Feature Qualifiers
Qualifiers provide additional information about features. They take
the form of a slash (/) followed by a qualifier name and, if
applicable, an equal sign (=) and a qualifier value. Feature
qualifiers begin at column 22.
Qualifiers convey many types of information. Their values can,
therefore, take several forms:
1. Free text;
2. Controlled vocabulary or enumerated values;
3. Citations or reference numbers;
4. Sequences;
5. Feature labels.
Text qualifier values must be enclosed in double quotation marks. The
text can consist of any printable characters (ASCII values 32-126
decimal). If the text string includes double quotation marks, each set
must be `escaped' by placing a double quotation mark in front of it
(e.g., /note="This is an example of ""escaped"" quotation marks").
Some qualifiers require values selected from a limited set of choices.
For example, the `/direction' qualifier has only three values `left,'
`right,' or `both.' These are called controlled vocabulary qualifier
values. Controlled qualifier values are not case sensitive; they can
be entered in any combination of upper- and lowercase without changing
their meaning.
Citation or published reference numbers for the entry should be
enclosed in square brackets ([]) to distinguish them from other
numbers.
A literal sequence of bases (e.g., "atgcatt") should be enclosed in
quotation marks. Literal sequences are distinguished from free text by
context. Qualifiers that take free text as their values do not take
literal sequences, and vice versa.
The `/label=' qualifier takes a feature label as its qualifier.
Although feature labels are optional, they allow unambiguous
references to the feature. The feature label identifies a feature
within an entry; when combined with the accession number and the name
of the data bank from which it came, it is a unique tag for that
feature. Feature labels must be unique within an entry, but can be the
same as a feature label in another entry. Feature labels are not case
sensitive; they can be entered in any combination of upper-and
lowercase without changing their meaning.
The following is a partial list of feature qualifiers.
/anticodon Location of the anticodon of tRNA and the amino acid
for which it codes
/bound_moiety Moiety bound
/citation Reference to a citation providing the claim of or
evidence for a feature
/codon Specifies a codon that is different from any found in the
reference genetic code
/codon_start Indicates the first base of the first complete codon
in a CDS (as 1 or 2 or 3)
/cons_splice Identifies intron splice sites that do not conform to
the 5'-GT... AG-3' splice site consensus
/db_xref A database cross-reference; pointer to related information
in another database. A description of all cross-references
can be found at:
http://www.ncbi.nlm.nih.gov/collab/db_xref.html
/direction Direction of DNA replication
/EC_number Enzyme Commission number for the enzyme product of the
sequence
/evidence Value indicating the nature of supporting evidence
/frequency Frequency of the occurrence of a feature
/function Function attributed to a sequence
/gene Symbol of the gene corresponding to a sequence region (usable
with all features)
/label A label used to permanently identify a feature
/map Map position of the feature in free-format text
/mod_base Abbreviation for a modified nucleotide base
/note Any comment or additional information
/number A number indicating the order of genetic elements
(e.g., exons or introns) in the 5 to 3 direction
/organism Name of the organism that is the source of the
sequence data in the record.
/partial Differentiates between complete regions and partial ones
/phenotype Phenotype conferred by the feature
/product Name of a product encoded by a coding region (CDS)
feature
/pseudo Indicates that this feature is a non-functional
version of the element named by the feature key
/rpt_family Type of repeated sequence; Alu or Kpn, for example
/rpt_type Organization of repeated sequence
/rpt_unit Identity of repeat unit that constitutes a repeat_region
/standard_name Accepted standard name for this feature
/transl_except Translational exception: single codon, the translation
of which does not conform to the reference genetic code
/translation Amino acid translation of a coding region
/type Name of a strain if different from that in the SOURCE field
/usedin Indicates that feature is used in a compound feature
in another entry
3.4.12.4 Cross-Reference Information
One type of information in the feature table lists cross-references to
the annual compilation of transfer RNA sequences in Nucleic Acids
Research, which has kindly been sent to us on CD-ROM by Dr. Sprinzl.
Each tRNA entry of the feature table contains a /note= qualifier that
includes a reference such as `(NAR: 1234)' to identify code 1234 in
the NAR compilation. When such a cross-reference appears in an entry
that contains a gene coding for a transfer RNA molecule, it refers to
the code in the tRNA gene compilation. Similar cross-references in
entries containing mature transfer RNA sequences refer to the
companion compilation of tRNA sequences published by D.H. Gauss and M.
Sprinzl in Nucleic Acids Research.
3.4.12.5 Feature Table Examples
In the first example a number of key names, feature locations, and
qualifiers are illustrated, taken from different sequences. The first
table entry is a coding region consisting of a simple span of bases
and including a /gene qualifier. In the second table entry, an NAR
cross-reference is given (see the previous section for a discussion of
these cross-references). The third and fourth table entries use the
symbols `<`and `>' to indicate that the beginning or end of the
feature is beyond the range of the presented sequence. In the fifth
table entry, the symbol `^' indicates that the feature is between
bases.
1 10 20 30 40 50 60 70 79
---------+---------+---------+---------+---------+---------+---------+---------
CDS 5..1261
/product="alpha-1-antitrypsin precursor"
/map="14q32.1"
/gene="PI"
tRNA 1..87
/note="Leu-tRNA-CAA (NAR: 1057)"
/anticodon=(pos:35..37,aa:Leu)
mRNA 1..>66
/note="alpha-1-acid glycoprotein mRNA"
transposon <1..267
/note="insertion element IS5"
misc_recomb 105^106
/note="B.subtilis DNA end/IS5 DNA start"
conflict 258
/replace="t"
/citation=[2]
---------+---------+---------+---------+---------+---------+---------+---------
1 10 20 30 40 50 60 70 79
Example 10. Feature Table Entries
The next example shows the representation for a CDS that spans more
than one entry.
1 10 20 30 40 50 60 70 79
---------+---------+---------+---------+---------+---------+---------+---------
LOCUS HUMPGAMM1 3688 bp ds-DNA PRI 15-OCT-1990
DEFINITION Human phosphoglycerate mutase (muscle specific isozyme) (PGAM-M)
gene, 5' end.
ACCESSION M55673 M25818 M27095
KEYWORDS phosphoglycerate mutase.
SEGMENT 1 of 2
.
.
.
FEATURES Location/Qualifiers
CAAT_signal 1751..1755
/gene="PGAM-M"
TATA_signal 1791..1799
/gene="PGAM-M"
exon 1820..2274
/number=1
/EC_number="5.4.2.1"
/gene="PGAM-M"
intron 2275..2377
/number=1
/gene="PGAM2"
exon 2378..2558
/number=2
/gene="PGAM-M"
.
.
.
//
LOCUS HUMPGAMM2 677 bp ds-DNA PRI 15-OCT-1990
DEFINITION Human phosphoglycerate mutase (muscle specific isozyme) (PGAM-M),
exon 3.
ACCESSION M55674 M25818 M27096
KEYWORDS phosphoglycerate mutase.
SEGMENT 2 of 2
.
.
.
FEATURES Location/Qualifiers
exon 255..457
/number=3
/gene="PGAM-M"
intron order(M55673:2559..>3688,<1..254)
/number=2
/gene="PGAM-M"
mRNA join(M55673:1820..2274,M55673:2378..2558,255..457)
/gene="PGAM-M"
CDS join(M55673:1861..2274,M55673:2378..2558,255..421)
/note="muscle-specific isozyme"
/gene="PGAM2"
/product="phosphoglycerate mutase"
/codon_start=1
/translation="MATHRLVMVRHGESTWNQENRFCGWFDAELSEKGTEEAKRGAKA
IKDAKMEFDICYTSVLKRAIRTLWAILDGTDQMWLPVVRTWRLNERHYGGLTGLNKAE
TAAKHGEEQVKIWRRSFDIPPPPMDEKHPYYNSISKERRYAGLKPGELPTCESLKDTI
ARALPFWNEEIVPQIKAGKRVLIAAHGNSLRGIVKHLEGMSDQAIMELNLPTGIPIVY
ELNKELKPTKPMQFLGDEETVRKAMEAVAAQGKAK"
.
.
.
//
---------+---------+---------+---------+---------+---------+---------+---------
1 10 20 30 40 50 60 70 79
Example 11. Joining Sequences
3.4.13 ORIGIN Format
The ORIGIN record may be left blank, may appear as `Unreported.' or
may give a local pointer to the sequence start, usually involving an
experimentally determined restriction cleavage site or the genetic
locus (if available). The ORIGIN record ends in a period if it
contains data, but does not include the period if the record is left
empty (in contrast to the KEYWORDS field which contains a period
rather than being left blank).
3.4.14 SEQUENCE Format
The nucleotide sequence for an entry is found in the records following
the ORIGIN record. The sequence is reported in the 5 to 3 direction.
There are sixty bases per record, listed in groups of ten bases
followed by a blank, starting at position 11 of each record. The
number of the first nucleotide in the record is given in columns 4 to
9 (right justified) of the record.
|