Molecular characterization of pregnancy-associated plasma protein-A by electrophoresis.
Gradient polyacrylamide gel electrophoresis, isoelectric focusing and multidimensional immunoelectrophoretic techniques have been applied in order to physico-chemically characterize pregnancy-associated plasma protein-A (PAPP-A). By lectin affinity immunoelectrophoresis, PAPP-A contained sialic acid, glucose/mannose and N-acetyl-alpha-D-galactosamine. Immunoelectrophoretic analyses after incubation with various glycolases confirmed these findings and demonstrated that PAPP-A contained glucuronic acid, perhaps in chondroitin sulphate moities, thus indicating that PAPP-A may be a proteoglycan rather than a glycoprotein. Analysis by metal chelate and dye ligand affinity immunoelectrophoresis demonstrated many similarities between PAPP-A and alpha 2-macroglobulin (alpha 2M). However, unlike alpha 2M, PAPP-A did not form immunologically reactive complexes when incubated with proteases. Furthermore, as demonstrated by autoradiographic studies, PAPP-A did not contain internal thiolester groups, thus indicating that PAPP-A cannot inhibit proteases by molecular entrapment and, despite the homotetrameric molecular conformation, PAPP-A and alpha 2M may not have evolved from a common ancestral protein.
Department of Obstetrics and Gynaecology, Royal North Shore Hospital, St. Leonards, Australia.
M J
MJ
Sinosich
D002413:Cations, Divalent; D002810:Chondroitinases and Chondroitin Lyases / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D005966:Glucuronidase / Q000378:metabolism; D006493:Heparin; D006801:Humans; D007122:Immunoelectrophoresis; D007525:Isoelectric Focusing; D007526:Isoelectric Point; D037102:Lectins; D046911:Macromolecular Substances; D008970:Molecular Weight; D009439:Neuraminidase / Q000378:metabolism; D011257:Pregnancy Proteins / Q000032:analysis*; D011266:Pregnancy-Associated Plasma Protein-A / Q000032:analysis* / Q000378:metabolism; D011268:Pregnancy-Specific beta 1-Glycoproteins / Q000032:analysis; D013917:Thrombin / Q000378:metabolism; D000520:alpha-Glucosidases / Q000378:metabolism; D000511:alpha-Macroglobulins / Q000032:analysis
D002413:Cations, Divalent; D037102:Lectins; D046911:Macromolecular Substances; D011257:Pregnancy Proteins; D011268:Pregnancy-Specific beta 1-Glycoproteins; D000511:alpha-Macroglobulins; D006493:Heparin; D009439:Neuraminidase; D000520:alpha-Glucosidases; D005966:Glucuronidase; D013917:Thrombin; D011266:Pregnancy-Associated Plasma Protein-A; D002810:Chondroitinases and Chondroitin Lyases