This is a family of sequences found in both bacteria and bacteriophages. This region is approximately 130 residues long and in some cases is found as part of the PVL (Panton-Valentine leukocidin) group of genes, which encode a member of the leukocidin group of bacterial toxins that kill leukocytes by creation of pores in the cell membrane. PVL appears to be a virulence factor associated with a number of human diseases.
Jiyao W et al.(2023). "The conserved domain database in 2023.",