ENTRY       EC 3.4.21.45
NAME        Complement Factor I
            Complement component C3b inactivator
            C3b inactivator
            C3b/C4b inactivator
            C3bINA
CLASS       Hydrolases
            Acting on peptide bonds (peptidases)
            Serine endopeptidases
REACTION    Inactivates complement subcomponents C3b, iC3b and C4b by
            proteolytic cleavage
SUBSTRATE   Complement component C3b
            Complement component iC3b
            Complement component C4b
            H2O
COFACTOR    Factor H
            Complement receptor CR1
            C4b-binding protein
COMMENT     Cleavage of complement subcomponent C3b requires its binding to
            cofactor Factor H or complement receptor CR1; cleavage of
            iC3b requires complement receptor CR1; cleavage of C4b requires
            C4b-binding protein.
DISEASE     MIM: 217030  I factor (complement); C3b inactivator deficiency (3)
MOTIF       PS: PS00134  [LIVM]-[ST]-A-[STAG]-H-C
            PS: PS00135  [DNSTAGC]-[GSTAPIMVQH]-x(2)-G-[DE]-S-G-[GS]-[SAPHV]-
                         [LIVMFYWH]-[LIVMFYSTANQH]
GENES       HSA: IF(Hs.36602)
DBLINKS     University of Geneva ENZYME DATA BANK: 3.4.21.45
            WIT (What Is There) Metabolic Reconstruction: 3.4.21.45
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