Assembled genomes from the Candidatus Pacearchaeota archaeon group and its close relatives, so far all uncultured, have a single archaeosortase, called pacearchaseosortase. A search protein archaeosortase targets, with a C-terminal domain resembling other archaeosortase and exosortase sorting signal regions, found this family as the best candidate. It is nearly always encoded by a gene found adjacent to the pacearchaseosortase gene. This dedicated arrangement, a sorting enzyme encoded next to its only predicted sorting substrate, suggests that members of this family, called PACE-CTERM, may be an important and abundant surface protein, most likely the major S-layer protein.
Jiyao W et al.(2023). "The conserved domain database in 2023.",