serping-1

As protease inhibitors, serpins have an array of functions including regulating blood clotting, the complement pathway, extracellular matrix remodeling, and cell motility. Serpin G1 is a serine protease inhibitor protein. It is the largest member among the serpin class of proteins. Remarkably, Serpin G1 has a 2-domain structure, unlike most family members. The C-terminal serpin domain is similar to other serpins, and this part of Serpin G1 provides the inhibitory activity. The N-terminal domain is not essential for Serpin G1 to inhibit proteinases and has no similarity to other proteins. The main function of Serpin G1 is the inhibition of the complement system to prevent spontaneous activation. Serpin G1 is an acute phase protein and circulates in blood at levels of around 0.25g L, whose levels rise 2-fold during inflammation. Although named after its complement inhibitory activity, Serpin G1 also inhibits proteinases of the fibrinolytic, clotting, and kinin pathways. Most notably, Serpin G1 play a potentially crucial role in regulating important physiological pathways including complement activation, blood coagulation, fibrinolysis and the generation of kinins. It is also the most important physiological inhibitor of fXIIa, chymotrypsin and plasma kallikrein.

SERPIN G1 is a member of the serpin family, The C-terminal serpin domain is similar to other serpins, and this part of C1-INH provides the inhibitory activity. SERPIN G1 is involved in the inhibition of the complement system to prevent spontaneous activation. SERPIN G1 may play a potentially crucial role in regulating important physiological pathways including complement activation, blood coagulation, fibrinolysis and the generation of kinins. SERPIN G1 prevents the proteolytic cleavage of later complement components C4 and C2 by C1 and MBL. SERPIN G1 is a very efficient physiological inhibitor of FXIIa, plasma kallikrein and fXIa, and could inhibit chymotrypsin and kallikrein. It forms a proteolytically inactive stoichiometric complex with the C1r or C1s proteases in the C1 complex of classical pathway of complement. Activation of the C1 complex is under control of the C1-inhibitor.