<p> This family represents the archaeal protein Kae1. Its partner Bud32 is fused with it in about half of the known archaeal genomes. The pair, which appears universal in the archaea, corresponds to EKC/KEOPS complex in eukaryotes. A recent characterisation of the member from <taxon tax_id="29292">Pyrococcus abyssi</taxon>, as an iron-binding, atypical DNA-binding protein with an apurinic lyase activity, challenges the common annotation of close homologs as O-sialoglycoprotein endopeptidase. The latter annotation is based on a characterised protein from the bacterium <taxon tax_id="75985">Mannheimia haemolytica</taxon>. </p> Kae1, peptidase M22-related