C1 -inhibitor

:is a protease family belonging to the serpin super family.

C1-inhibitor has a 2-domain structure. The C-terminal serpin domain is similar to other serpins, which is the part of C1-inhibitor that provides the inhibitory activity. The N-terminal domain is not essential for C1-inhibitor to inhibit proteases. 

 main function : inhibition of the complement system to prevent spontaneous activation.

 : C1-inhibitor irreversibly binds to and inactivates C1r and C1s proteases in the C1 complex of classical pathway of complement.

 C1-inhibitor also inhibits proteases of the fibrinolytic, clotting, and kinin pathways. 

 Hereditary angioedema

Deficiency of this protein is associated with hereditary angioedema(HAE).

This problem affects the blood vessels. People with hereditary angioedema can develop rapid swelling of the hands, feet, limbs, face, intestinal tract, larynx.

Factor H

 is a member of the regulators of complement activation family and is a complement control protein.

main function:  is to regulate the alternative pathway of the complement system.

:by possessing both cofactor activity for the factor I mediated C3b cleavage, and decay accelerating activity against the alternative pathway C3-convertase, C3bBb.

it binds to glycosaminoglycans (GAGs) that are generally present on host cells but not, normally, on pathogen surfaces.