title: Human pregnancy zone protein and alpha 2-macroglobulin. High-affinity binding of complexes to the same receptor on fibroblasts and characterization by monoclonal antibodies.
abstract: Pregnancy zone protein (PZP) was isolated from late pregnancy serum and examined for binding to normal skin fibroblasts in culture. A high-affinity binding site on these cells is demonstrated for PZP reacted with methylamine. Experiments with alpha 2-macroglobulin (alpha 2M) and PZP, both modified by methylamine, showed this receptor to be identical to the previously characterized receptor for alpha 2M-proteinase complexes (Van Leuven, F., Cassiman, J.J., and Van den Berghe, H. (1979) J. Biol. Chem. 254, 5155-5160). With available monoclonal antibodies directed toward alpha 2M and prepared toward PZP, only a limited cross-reaction was observed. We obtained a monoclonal antibody which defines a neo-antigenic site on PZP-methylamine, completely analogous to the monoclonal antibody F2B2, which was previously shown to define a neo-antigenic site on alpha 2M complexes (Marynen, P., Van Leuven, F., Cassiman, J.J., and Van den Berghe, H. (1981) J. Immunol. 127, 1782-1786). These results provide evidence for the homologous function of alpha 2M and PZP as proteinase scavengers. The need for an extra proteinase inhibitor of the alpha 2M-type in pregnancy is discussed. The monoclonal antibodies now available will prove helpful in quantitation and eventually isolation of proteinase complexes of alpha 2M and PZP.
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D000936:Antigen-Antibody Complex; D002478:Cells, Cultured; D005260:Female; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D026503:Low Density Lipoprotein Receptor-Related Protein-1; D051379:Mice; D008807:Mice, Inbred BALB C; D011247:Pregnancy; D011257:Pregnancy Proteins / Q000302:isolation & purification / Q000378:metabolism*; D011971:Receptors, Immunologic / Q000378:metabolism*; D012867:Skin / Q000378:metabolism; D000511:alpha-Macroglobulins / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D000911:Antibodies, Monoclonal; D000936:Antigen-Antibody Complex; D026503:Low Density Lipoprotein Receptor-Related Protein-1; D011257:Pregnancy Proteins; D011971:Receptors, Immunologic; D000511:alpha-Macroglobulins