Structural domains comprising this superfamily share the structure of the MEROPS peptidase family S13 (D-Ala-D-Ala carboxypeptidase C, clan SE). D-Ala-D-Ala carboxypeptidase C is involved in the metabolism of cell components PMID:1741619 and it is synthesised with a leader peptide which targets it to the cell membrane PMID:7845208. After cleavage of the leader peptide, the enzyme is retained in the membrane by a C-terminal anchor PMID:7845208. There are three families of serine-type D-Ala-D-Ala peptidase (designated S11, S12 and S13), which are also known as low molecular weight penicillin-binding proteins PMID:7845208. Family S13 comprises D-Ala-D-Ala peptidases that have sufficient sequence similarity around their active sites to assume a distant evolutionary relationship to other clan members; members of the S13 family also bind penicillin and have D-amino-peptidase activity. Proteases of family S11 have exclusive D-Ala-D-Ala peptidase activity, while some members of S12 are C beta-lactamases PMID:7845208.