This family consists of immunoglobulin A1 protease proteins. The immunoglobulin A1 protease cleaves immunoglobulin IgA and is found in pathogenic bacteria such as Neisseria gonorrhoeae. Not all of the members of this family are IgA proteases. EspP from Escherichia coli O157:H7 cleaves human coagulation factor V and is a hemoglobin protease from E. coli EB1. This group of serine peptidases belong to the MEROPS peptidase family S6 (clan PA(S)).