Pregnancy-associated plasma protein-A (PAPP-A) inhibits thrombin-induced coagulation of plasma.
Concentrations of immunoreactive PAPP-A have been found significantly lower in the serum as compared to heparin or EDTA plasma from the same patients. After coagulation significant amounts of PAPP-A remain associated with the clot. Purified PAPP-A inhibits thrombin induced coagulation of plasma. This inhibition cannot be attributed to a direct effect of PAPP-A on thrombin. It is exerted via an activation of endogenous antithrombin III since the inhibitory effect of PAPP-A on thrombin induced coagulation in a euglobulin system can be observed only if antithrombin III is added. The fact that protamine sulphate is capable of neutralizing the inhibitory effects of PAPP-A made us postulate that PAPP-A, like heparin, possesses strongly acidic residues which bind to protamine.
D000818:Animals; D000990:Antithrombin III / Q000494:pharmacology; D012103:Batroxobin / Q000494:pharmacology; D001777:Blood Coagulation / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004492:Edetic Acid / Q000494:pharmacology; D005260:Female; D006493:Heparin / Q000494:pharmacology; D006736:Horses; D006801:Humans; D010949:Plasma / Q000032:analysis / Q000187:drug effects*; D011247:Pregnancy; D011257:Pregnancy Proteins / Q000494:pharmacology*; D011266:Pregnancy-Associated Plasma Protein-A / Q000008:administration & dosage / Q000032:analysis / Q000378:metabolism / Q000494:pharmacology*; D011479:Protamines / Q000494:pharmacology; D011863:Radioimmunoassay; D013917:Thrombin / Q000037:antagonists & inhibitors* / Q000494:pharmacology
D011257:Pregnancy Proteins; D011479:Protamines; D000990:Antithrombin III; D006493:Heparin; D004492:Edetic Acid; D012103:Batroxobin; D013917:Thrombin; D011266:Pregnancy-Associated Plasma Protein-A