Members of this family of bacterial domains are predominantly found in transglutaminase and transglutaminase-like proteins. Their exact function is, as yet, unknown, but they are likely to act as amidoligase enzymes Protein in this family are found in conserved gene neighborhoods encoding a glutamine amidotransferase-like thiol peptidase (in proteobacteria) or an Aig2 family cyclotransferase protein (in firmicutes).
Jiyao W et al.(2023). "The conserved domain database in 2023.",