Complement activation pathways

Ig: immunoglobulin; LPS: lipopolysaccharide; C1q: complement component 1q; C1r: complement component 1r; C1s: complement component 1s; MBL: mannose-binding lectin; MASP: mannose-binding lectin-associated proteases; C1-est inhib: C1 esterase inhibitor; C4bp: C4-binding protein; B: factor B; CR1: complement receptor 1; DAF: decay accelerating factor; MCP: membrane cofactor protein; MAC: membrane attack complex.
* Factor H also acts as a cofactor for factor I to regulate the C3 and C5 convertases.