The Ciliate Ortholog Database computes and stores the putative orthologous gene groups in completed ciliate genomes. Ciliates are a group of protists that possess two nuclei: a germline micronucleus and a somatic macronucleus. Currently, the macronuclear genomes of two ciliates have been completely sequenced: Tetrahymena thermophila and Paramecium tetraurelia.

The current version of the database contains the ortholog groups between T. thermophila and P. tetraurelia identified using InParanoid program, as well as other publicly available ciliate sequence data whose best hit is a member of the ortholog groups. These public data includes all the ciliate protein entries in GenBank and the sequenced macronuclear chromosomes in the ongoing Oxytricha trifallax genome project. As more ciliate genomic and EST sequences become available in the near future, this database will keep expanding the scope of the ortholog computation and storage.