Clustering of DNA replication and ribosome-associated genes in archaeal genomes. Orthologous genes are indicated in the same color. Each gene is denoted by the name of the protein it encodes (see the key at the top). COG2047 encodes an uncharacterized protein of the ATP-grasp superfamily; this COG is absent from Crenarchaea and N. equitans. Species or cell lineages that have the same genomic environment are listed and the number of corresponding genomes is given in parentheses. Genes are not shown to scale.