Complement Factor I
MESHD017244
A plasma serine proteinase that cleaves the alpha-chains of C3b and C4b in the presence of the cofactors COMPLEMENT FACTOR H and C4-binding protein, respectively. It is a 66-kDa glycoprotein that converts C3b to inactivated C3b (iC3b) followed by the release of two fragments, C3c (150-kDa) and C3dg (41-kDa). It was formerly called KAF, C3bINF, or enzyme 3b inactivator.
Synonyms
- C3b-C4b Inactivator
- C3b C4b Inactivator
- Inactivator, C3b-C4b
- C4b-C3b-INA
- C4b C3b INA
- Complement 3b-Complement 4b Inactivator
- Complement 3b Complement 4b Inactivator
- C4bC3bINA
- Complement C4b-C3b Inactivator
- C4b-C3b Inactivator, Complement
- Complement C4b C3b Inactivator
- Inactivator, Complement C4b-C3b
- C3b Inactivator
- Inactivator, C3b
Source last updated 2026-05-24T15:25:55.068Z