Serum α2-pregnancy related protein

SP3 is also called Pregnancy Zone Protein (PZP), which is synthesized by liver and trophoblast cells. In vitro experiments have shown that certain non-hepatocellular tumor cell lines can also be synthesized. The syncytiotrophoblast, B lymphocytes, and monocytes all contain this protein. Their physiological functions are not well understood. Proteolytic enzymes in the blood circulation bind to SP3 to form complexes and are subsequently eliminated. SP3 and & alpha; 2 macroglobulin may be homologues.