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complement C1s
activated by C1r to form C1s(dimer)
Function:
- activated by C1r to form C1s(dimer)
- C1s B chain is a serine protease that combines with C1q & C1r to form C1, the first component of the complement classical pathway
- C1r activates C1s so that it can, in turn, activate C2 & C4
- cleavage of Arg-|-Ala bond in complement component C4 to form C4a & C4b, & Lys(or Arg)-|-Lys bond in complement C2 to form C2a & C2b: the 'classical' pathway C3-convertase [5]
-
- inhibited by SERPING1 [5]
Kinetic parameters:
- KM=12.3 uM for complement component C2 (at 37 degrees Celsius) [5]
- KM=1.9 uM for complement component C4 (at 37 degrees Celsius) [5]
Structure:
- belongs to the peptidase S1 family
- contains 2 CUB domains
- contains 1 EGF-like domain
- contains 1 peptidase S1 domain
- contains 2 Sushi (CCP/SCR) domains
- activated C1s is an disulfide-linked heterodimer of a heavy chain & a light chain [6]
Pathology:
- complement C1s deficiency [7]
Interactions
molecular events
Related
angioneurotic edema; angioedema; atrophedema; Bannister's disease; Milton's disease; Quincke's disease; periodic or Quincke's edema; giant urticaria or hives; urticaria gigans, gigantea, or tuberosa.
General
complement-activating enzyme
complement
inter alpha globulin
oligomerizing protein
serine protease trypsin family
Properties
CONFIGURATION: dimer
COMPARTMENT: membrane
MOTIF: active site
EGF domain
allosteric site (2)
FOR-BINDING-OF: complement C1 inhibitor
STATE: active state
Database Correlations
OMIM correlations
MORBIDMAP 120580
UniProt P09871
PFAM correlations
Entrez Gene 716
KEGG correlations
ENZYME 4.21.42
References
- Baron M, Norman DG, Campbell ID.
Protein modules.
Trends Biochem Sci. 1991 Jan;16(1):13-7. Review.
PMID: 2053133
- Clinical Diagnosis & Management by Laboratory
Methods, J.B. Henry (ed), W.B. Saunders Co.,
Philadelphia, PA. 1991, pg 832
- UniProt :accession P09871
- C1Sbase; Note: C1S mutation db
http://bioinf.uta.fi/C1Sbase/
- Rossi V, Cseh S, Bally I, Thielens NM, Jensenius JC, Arlaud GJ.
Substrate specificities of recombinant mannan-binding lectin-
associated serine proteases-1 and -2.
J Biol Chem. 2001 Nov 2;276(44):40880-7.
PMID: 11527969
- Hess D, Schaller J, Rickli EE.
Identification of the disulfide bonds of human complement C1s.
Biochemistry. 1991 Mar 19;30(11):2827-33.
PMID: 2007122
- Dragon-Durey MA, Quartier P, Fremeaux-Bacchi V et al
Molecular basis of a selective C1s deficiency associated with
early onset multiple autoimmune diseases.
J Immunol. 2001 Jun 15;166(12):7612-6.
PMID: 11390518
Component-of
complement-1 (C1)