KEGG OC (KEGG Ortholog Cluster) is a novel database of ortholog clusters (OCs) based on the whole genome comparison. The OCs were constructed by applying a novel clustering method to all possible protein coding genes in all complete genomes, based on their amino acid sequence similarities. KEGG OC has the following original features in terms of coverage, efficiency, and usability. First, it consists of all fully sequenced genomes of a wide range of organisms from three domains (eukaryotes, bacteria, and archaea). Second, it is computationally efficient to calculate OCs, which makes it possible to regularly update the contents. Third, it is compatible with the KEGG database, which provides an easy way to link the OCs with KEGG PATHWAY, BRITE functional hierarchies, KEGG MODULE, KEGG MEDICUS, and many more.

OC search

ID or terms query

ex. hsa:362, K04517, M00170, pyruvate dehydrogenase org=bsu

Amino acid sequence query

ex. hsa:5162


Number of organisms:3,836
Number of eukaryotes:303
Number of bacteria:3,341
Number of archaea:192
Number of sequences:15,950,370
Number of clusters:1,521,869

Cluster typeSingletonMultipleTotal
domain common0593593
eukaryotes, bacteria04,3984,398
eukaryotes, archaea01,0741,074
bacteria, archaea03,6413,641

ver. 2015-06-23