Members of this protein family represent a distinct clade among the larger set of proteins that belong to families TIGR00702 and pfam02624. Proteins from this clade are found in genome sequence if and only if the species sequenced is one of the methanogens. All methanogens belong to the archaea; some but not all of those sequenced are hyperthermophiles. This protein family was detected by the method of partial phylogenetic profiling (see Haft, et al., 2006).