Factor I inactivates Factor H-boundC3b

Stable Identifier
R-HSA-977371
Type
Reaction [transition]
Species
Homo sapiens
Compartment
plasma membrane, extracellular region
ReviewStatus
5/5
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Factor I inactivates Factor H-boundC3b
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Following the displacement of Bb from C3bBb, Factor I (CFI) cleaves Factor H-bound C3b producing iC3b, which remains bound to the membrane. The majority of the C3b alpha chain is retained as two fragments which are tethered to the beta chain by disulphide bonds. iC3b is proteolytically inactive and cannot contribute to the complement cascade process, though it still contributes to opsonization.
Literature References
PubMed ID Title Journal Year
3848661 C3 nephritic factor protects bound C3bBb from cleavage by factor I and human erythrocytes

Medof, ME, Mold, C

Mol Immunol 1985
6219696 Kinetic and thermodynamic analysis of the control of C3b by the complement regulatory proteins factors H and I

Pangburn, MK, Muller-Eberhard, HJ

Biochemistry 1983
Participants
Input
Output
Participates
as an event of
Catalyst Activity

serine-type endopeptidase activity of CFI:CFH,FHR3:C3b [plasma membrane]

Physical Entity
CFI:CFH,FHR3:C3b [plasma membrane] (Homo sapiens)
Activity
serine-type endopeptidase activity (GO:0004252)
Orthologous Events
Complement factor I inactivates surface-bound C3b (Gallus gallus)
Factor I inactivates Factor H-boundC3b (Bos taurus)
Factor I inactivates Factor H-boundC3b (Canis familiaris)
Factor I inactivates Factor H-boundC3b (Gallus gallus)
Factor I inactivates Factor H-boundC3b (Sus scrofa)
Factor I inactivates Factor H-boundC3b (Xenopus tropicalis)
Authored
Jupe, S  (2010-10-26)
Reviewed
Fraczek, LA  (2012-02-13)
Bradley, DT  (2012-02-13)
Created
Jupe, S  (2010-10-18)
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