Serpin A5

Serpin A5, historically called protein C inhibitor (PCI), is a secreted plasma serpin synthesized mainly in the liver, with high local expression in the placenta, kidney, and reproductive tract. Its reactive center loop inhibits the anticoagulant serine protease activated protein C as well as urokinase, tissue plasminogen activator, and several other proteases, placing it at the interface of coagulation and fibrinolysis. Plasma levels rise during pregnancy and the acute-phase response. PCI also functions intracellularly and has been linked to protection against viral infection and to tissue remodeling in the reproductive system. Recombinant Serpin A5 supports coagulation protease inhibition assays and placental biology research.