KEGG is a comprehensive knowledge base for systematic analysis of gene functions in terms of gene and molecule networks. It includes the PATHWAY database, which contains graphical diagrams of biochemical pathways, including most known metabolic pathways and some regulatory pathways. The pathway information is also represented by ortholog group tables summarizing gene groups among different organisms. KEGG maintains the GENES database for gene catalogs of all organisms with complete genomes and selected organisms with partial genomes, continuously re-annotated, as well as the LIGAND database for chemical compounds and enzymes. Each gene catalog is associated with a graphical genome map for chromosomal locations represented by Java applet. KEGG also develops and provides computational tools for reconstructing biochemical pathways from complete genome sequences and predicting gene regulatory networks from gene expression profiles. The KEGG databases are daily updated and freely available at http://www.genome.ad.jp/kegg/. The KEGG project, initiated in 1995 under Japan's Human Genome Program, aims to automate human reasoning steps for interpreting biological meaning encoded in sequence data. It focuses on reconstructing biological systems from complete gene sets and understanding how genes and molecules are networked. The objectives of KEGG include computerizing current knowledge of genetics, biochemistry, and molecular biology in terms of molecular interaction pathways, maintaining gene catalogs for all complete genomes and some partial genomes, maintaining a catalog of chemical elements, compounds, and substances in living cells, and providing new informatics technologies for predicting biological systems and designing experiments. The KEGG databases are divided into pathway (functional) information and genomic (structural) information. The PATHWAY database contains graphical diagrams of biochemical pathways, with about 90 reference maps for metabolic pathways. The GENES database contains gene information for all organisms, organized as a flat-file database. The genome map represents a one-dimensional network of genes physically located in a genome, and is linked to pathway maps. The comparative genome map helps identify clusters of orthologous genes and functional annotation of newly sequenced genomes. The ortholog group tables summarize functional, physical, and evolutionary correlations among species. The LIGAND database stores information on chemical compounds, enzyme molecules, and reactions. KEGG provides tools for pathway reconstruction using reference maps and binary relations. It also offers tools for searching and analyzing pathway and genome maps. The KEGG databases are available online and can be accessed via FTP. The KEGG project is supported by the Japanese Ministry of Education, Science, Sports and Culture.KEGG is a comprehensive knowledge base for systematic analysis of gene functions in terms of gene and molecule networks. It includes the PATHWAY database, which contains graphical diagrams of biochemical pathways, including most known metabolic pathways and some regulatory pathways. The pathway information is also represented by ortholog group tables summarizing gene groups among different organisms. KEGG maintains the GENES database for gene catalogs of all organisms with complete genomes and selected organisms with partial genomes, continuously re-annotated, as well as the LIGAND database for chemical compounds and enzymes. Each gene catalog is associated with a graphical genome map for chromosomal locations represented by Java applet. KEGG also develops and provides computational tools for reconstructing biochemical pathways from complete genome sequences and predicting gene regulatory networks from gene expression profiles. The KEGG databases are daily updated and freely available at http://www.genome.ad.jp/kegg/. The KEGG project, initiated in 1995 under Japan's Human Genome Program, aims to automate human reasoning steps for interpreting biological meaning encoded in sequence data. It focuses on reconstructing biological systems from complete gene sets and understanding how genes and molecules are networked. The objectives of KEGG include computerizing current knowledge of genetics, biochemistry, and molecular biology in terms of molecular interaction pathways, maintaining gene catalogs for all complete genomes and some partial genomes, maintaining a catalog of chemical elements, compounds, and substances in living cells, and providing new informatics technologies for predicting biological systems and designing experiments. The KEGG databases are divided into pathway (functional) information and genomic (structural) information. The PATHWAY database contains graphical diagrams of biochemical pathways, with about 90 reference maps for metabolic pathways. The GENES database contains gene information for all organisms, organized as a flat-file database. The genome map represents a one-dimensional network of genes physically located in a genome, and is linked to pathway maps. The comparative genome map helps identify clusters of orthologous genes and functional annotation of newly sequenced genomes. The ortholog group tables summarize functional, physical, and evolutionary correlations among species. The LIGAND database stores information on chemical compounds, enzyme molecules, and reactions. KEGG provides tools for pathway reconstruction using reference maps and binary relations. It also offers tools for searching and analyzing pathway and genome maps. The KEGG databases are available online and can be accessed via FTP. The KEGG project is supported by the Japanese Ministry of Education, Science, Sports and Culture.