Members of this family of proteins, with average length of 210, have no invariant residues but five predicted transmembrane segments. Strangely, most members occur in groups of consecutive paralogous genes. A striking example is a set of eleven encoded consecutively, head-to-tail, in Staphylococcus aureus strain COL.
Jiyao W et al.(2023). "The conserved domain database in 2023.",