ⓘ Complement factor I

                                     

ⓘ Complement factor I

Complement factor I, also known as C3b/C4b inactivator, is a protein that in humans is encoded by the CFI gene. Complement factor I is a protein of the complement system, first isolated in 1966 in guinea pig serum, that regulates complement activation by cleaving cell-bound or fluid phase C3b and C4b. It is a soluble glycoprotein that circulates in human blood at an average concentration of 35 μg/mL.

                                     
  • complement component 3, complement factor B, and complement factor I as well as deletion of complement factor H - related 3 and complement factor H - related 1 also
  • Factor I may refer to: Complement factor I a protein of the complement system. Fibrinogen, a protein involved in blood coagulation.
  • Complement factor B is a protein that in humans is encoded by the CFB gene. This gene encodes complement factor B, a component of the alternative pathway
  • called complement factor I cleaves C3b into its inactive form, i C3b. Factor I requires a C3b - binding protein cofactor such as complement factor H, CR1
  • Factor H is a member of the regulators of complement activation family and is a complement control protein. It is a large 155 kilodaltons soluble glycoprotein
  • agent. Factor I can cleave C3b into C3c and C3d, the latter of which plays a role in enhancing B cell responses. In the alternative complement pathway
  • to complement regulator I protein. It is responsible for the clumping of blood plasma observed when adding S. aureus to human plasma. Clumping factor can
  • complement factor I cleaves C3b. Complement receptors on white blood cells are able to bind i C3b, so i C3b functions as an opsonin. Unlike intact C3b, i C3b cannot
  • of C2 and factor B British Medical Bulletin. 43 1 37 49. PMID 3315100. Yu CY 1999 Molecular genetics of the human MHC complement gene cluster
  • C3a is one of the proteins formed by the cleavage of complement component 3 the other is C3b. C3a is a 77 residue anaphylatoxin that binds to the C3a