Table 2:
The Complement System and Immune Regulation
| Protease/Inhibitor | Uniprot | Action |
|---|---|---|
| C1R (Complement C1r subcomponent, Classical) | P00736 | Cleaves/Activates C1s |
| C1S (Complement C1s subcomponent, Classical) | P09871 | Cleaves/Activates C2 and C4 |
| C2a (Complement C2, C1s cleavage product) | P06681 | Combines with C4b to form C3 convertase (classical, lectin) |
| Factor D (Complement factor D, Bb fragment) | P00746 | Cleaves/Activates Complement Factor B |
| Factor B (Complement factor B, Bb fragment) | P00751 | Cleavage Product Bb combines with C3b to form C3 Convertase (Alternative) |
| C3-convertase (Classical, Lectin: C4bC2a) | Cleaves C3 into the anaphylatoxin C3a and the opsonin C3b | |
| C3-convertase (Alternative: C3bBb) | Cleaves C3 into the anaphylatoxin C3a and the opsonin C3b | |
| C3-convertase (Aqueous: C3:H2O) | Cleaves C3 into the anaphylatoxin C3a and the opsonin C3b | |
| C5-convertase (Classical: Cell Membrane, C4b2b3b) | Cleaves C5 into the anaphylatoxin C5a and the MAC component C5b | |
| C5-convertase (Alternative: Cell Membrane, C3bBbC3b) | Cleaves C5 into the anaphylatoxin C5a and the MAC component C5b | |
| C5-convertase (Classical: Fluid, C4b2boxy3b) | Cleaves C5 into the anaphylatoxin C5a and the MAC component C5b | |
| MASP 1 (Mannan-binding lectin serine protease 1) | P48740 | Activates MASP2 or C2 or C3 |
| MASP 2 (Mannan-binding lectin serine protease 2) | O00187 | Cleaves/Activates C2 and C4 |
| MASP 3 (Mannan-binding lectin serine protease 3) | P48740* | Cleaves/Activates complement pro-factor D *Alternative Splicing Product |
| C1-inhibitor (Plasma protease C1 inhibitor)* | P05155 | Complexes with/Inactivates C1r, C1s, MASP 1, MASP 2, chymotrypsin, kallikrein, fXIa, FXIIa |
| * complement activation, blood coagulation, fibrinolysis and the generation of kinins | ||
| Factor I (Complement factor I) | P05156 | Cleaves/Inactivates C3b, iC3b and C4b |
Complement System and Immune Regulation: Activities and uniprot ID codes (where applicable) of proteases, protease inhibitors, and cofactors associated with the complement system and immune regulation.