title: KEGG OC: a large-scale automatic construction of taxonomy-based ortholog clusters.
abstract: The identification of orthologous genes in an increasing number of fully sequenced genomes is a challenging issue in recent genome science. Here we present KEGG OC (http://www.genome.jp/tools/oc/), a novel database of ortholog clusters (OCs). The current version of KEGG OC contains 1 176 030 OCs, obtained by clustering 8 357 175 genes in 2112 complete genomes (153 eukaryotes, 1830 bacteria and 129 archaea). The OCs were constructed by applying the quasi-clique-based clustering method to all possible protein coding genes in all complete genomes, based on their amino acid sequence similarities. It is computationally efficient to calculate OCs, which enables to regularly update the contents. KEGG OC has the following two features: (i) It consists of all complete genomes of a wide variety of organisms from three domains of life, and the number of organisms is the largest among the existing databases; and (ii) It is compatible with the KEGG database by sharing the same sets of genes and identifiers, which leads to seamless integration of OCs with useful components in KEGG such as biological pathways, pathway modules, functional hierarchy, diseases and drugs. The KEGG OC resources are accessible via OC Viewer that provides an interactive visualization of OCs at different taxonomic levels.
authors.affiliation: Center for Transdisciplinary Research, Niigata University, 1-757 Asahimachi-dori, Chuo-ku, Niigata 951-8585, Japan.
authors.forename: Akihiro
authors.initials: A
authors.lastname: Nakaya
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Katayama
authors.forename: Masumi
authors.initials: M
authors.lastname: Itoh
authors.forename: Kazushi
authors.initials: K
authors.lastname: Hiranuka
authors.forename: Shuichi
authors.initials: S
authors.lastname: Kawashima
authors.forename: Yuki
authors.initials: Y
authors.lastname: Moriya
authors.forename: Shujiro
authors.initials: S
authors.lastname: Okuda
authors.forename: Michihiro
authors.initials: M
authors.lastname: Tanaka
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Tokimatsu
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Yamanishi
authors.forename: Akiyasu C
authors.initials: AC
authors.lastname: Yoshizawa
authors.forename: Minoru
authors.initials: M
authors.lastname: Kanehisa
authors.forename: Susumu
authors.initials: S
authors.lastname: Goto
mesh_terms: D000465:Algorithms; D002965:Classification / Q000379:methods; D016000:Cluster Analysis; D030541:Databases, Genetic; D056890:Eukaryota / Q000235:genetics; D005796:Genes; D019766:Genes, Archaeal; D005798:Genes, Bacterial; D020745:Genome, Archaeal; D016680:Genome, Bacterial; D023281:Genomics / Q000379:methods; D020407:Internet; D017386:Sequence Homology, Amino Acid