The GO Consortium makes ontology and gene association data available as RDF-XML, which can be downloaded from the GO database archive. The document type definition (DTD) is available from GO CVS web or from the directory go/www/xml-dtd/ in the GO CVS repository.

Sample data

Here's a GO RDF-XML snapshot (with some lines wrapped for legibility):

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE go:go PUBLIC "-//Gene Ontology//Custom XML/RDF Version 2.0//EN"

<go:go xmlns:go="http://www.geneontology.org/dtd/go.dtd#"
        <go:term rdf:about="http://www.geneontology.org/go#GO:0000001">
            <go:name>mitochondrion inheritance</go:name>
            <go:synonym>mitochondrial inheritance</go:synonym>
            <go:definition>The distribution of mitochondria, including the
            mitochondrial genome, into daughter cells after mitosis or meiosis,
            mediated by interactions between mitochondria and the cytoskeleton.
            <go:is_a rdf:resource="http://www.geneontology.org/go#GO:0048308" />
            <go:part_of rdf:resource="http://www.geneontology.org/go#GO:0009530" />
                rdf:resource="http://www.geneontology.org/go#GO:0006312" />
        <go:term rdf:about="http://www.geneontology.org/go#GO:0000002">
            <go:name>mitochondrial genome maintenance</go:name>
            <go:definition>The maintenance of the structure and integrity of the
            mitochondrial genome; includes replication and segregation of the
            mitochondrial chromosome.</go:definition>
            <go:is_a rdf:resource="http://www.geneontology.org/go#GO:0007005" />
            <go:dbxref rdf:parseType="Resource">
            <go:dbxref rdf:parseType="Resource">
        <go:term rdf:about="http://www.geneontology.org/go#GO:0000003">
            <go:synonym>reproductive physiological process</go:synonym>
            <go:definition>The production by an organism of new individuals that
            contain some portion of their genetic material inherited from that
            <go:is_a rdf:resource="http://www.geneontology.org/go#GO:0008150" />
            <go:dbxref rdf:parseType="Resource">

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RDF-XML Format Guide

The basic unit of the GO RDF-XML database is GO:termid. Owing to limitations of the XML id and idref attributes (for instance, multiple parentage cannot be represented), the linking mechanism is RDF. RDF provides a much more flexible system for representing trees. To follow the links, note that term mitochondrion inheritance ; GO:0000001 has the attribute

<go:term rdf:about="http://www.geneontology.org/go#GO:0000001">

This is roughly equivalent to

<go:term id="go#GO:0000001">

In rdf, URLs are used as IDs to make them universally unique. Now, note that term mitochondrion inheritance ; GO:0000001 has the tag

<go:is_a rdf:resource="http://www.geneontology.org/go#GO:0048308" />

This tag represents the relationship "GO:0000001 isa GO:0048308", i.e. GO:0000001 is a subtype of GO:0048308. Other types of relationship are also possible; in these cases, isa is substituted with the appropriate string; for example:

<go:part_of rdf:resource="http://www.geneontology.org/go#GO:0009530" />
<go:negatively_regulates rdf:resource="http://www.geneontology.org/go#GO:0006312" />

These lines show the relationships GO:0000001 part of GO:0009530 and GO:0000001 negatively regulates GO:0006312 respectively. See the GO relations documentation for the different relations used in GO.

In addition, each term can have one go:name, go:accession, go:definition, or multiple go:dbxrefs or go:associations. go:name, go:accession and go:definition are self-explanatory. go:dbxref represents the term in an external database, and go:association represents the gene associations of each term. go:association can have both go:evidence, which holds a go:dbxref to the evidence supporting the association, and a go:gene_product, which has the gene symbol and go:dbxref.

DTD Download

The RDF-XML DTD is available to download.

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