Activation of C1r

Stable Identifier
R-HSA-173626
Type
Reaction
Species
Homo sapiens
Compartment
extracellular region, plasma membrane
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Activation of C1r
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C1 activation requires interaction with two separate Fc domains, so pentavalent IgM antibody is far more efficient at complement activation than IgG antibody (Muller-Eberhard and Kunkel 1961). Antibody binding results in a conformational change in the C1r component of the C1 complex and a proteolytic cleavage of C1r, activating it (Ziccardi and Cooper 1976). This reaction is irreversible under physiological conditions.

Literature References
PubMed ID Title Journal Year
1249422 Activation of C1r by proteolytic cleavage

Cooper, NR, Ziccardi, RJ

J Immunol 1976
Participants
Input
Output
Participates
as an event of
Catalyst Activity

serine-type endopeptidase activity of Antigen:IgG:C1Q:2xC1R:2xC1S [plasma membrane]

Physical Entity
Antigen:IgG:C1Q:2xC1R:2xC1S [plasma membrane] (Homo sapiens)
Activity
serine-type endopeptidase activity (GO:0004252)
This event is regulated
Positively by
Regulator
C-reactive protein pentamer:phosphocholine:C1Q [extracellular region] (Homo sapiens)
Orthologous Events
Activation of C1r (Bos taurus)
Activation of C1r (Canis familiaris)
Activation of C1r (Danio rerio)
Activation of C1r (Gallus gallus)
Activation of C1r (Mus musculus)
Activation of C1r (Rattus norvegicus)
Activation of C1r within the C1complement complex (Gallus gallus)
Authored
de Bono, B  (2004-08-04)
Reviewed
D'Eustachio, P  (2006-07-03)
Created
de Bono, B  (2006-02-15)
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