The metallocarboxypeptidase family of enzymes is divided into 2 subfamilies based on sequence similarities. The pancreatic carboxypeptidase-like and the regulatory B-type carboxypeptidase subfamilies. Carboxypeptidase D has been identified as a regulatory B-type carboxypeptidase. CPD is a homolog of duck gp180, a hepatitis B virus-binding protein.
