Names & Taxonomy
- Uniprot ID:
- P09871
- Entry Name:
- C1S_HUMAN
- Status:
- reviewed
- Protein Names:
- Complement C1s subcomponent (EC 3.4.21.42) (C1 esterase) (Complement component 1 subcomponent s) [Cleaved into: Complement C1s subcomponent heavy chain; Complement C1s subcomponent light chain]
- Gene Names:
- C1S
- Gene Names Primary:
- C1S
- Organism:
- Homo sapiens (Human)
Structure
- Length:
- 688
- Sequence:
- MWCIVLFSLLAWVYAEPTMYGEILSPNYPQAYPSEVEKSWDIEVPEGYGIHLYFTHLDIELSENCAYDSVQIISGDTEEGRLCGQRSSNNPHSPIVEEFQVPYNKLQVIFKSDFSNEERFTGFAAYYVATDINECTDFVDVPCSHFCNNFIGGYFCSCPPEYFLHDDMKNCGVNCSGDVFTALIGEIASPNYPKPYPENSRCEYQIRLEKGFQVVVTLRREDFDVEAADSAGNCLDSLVFVAGDRQFGPYCGHGFPGPLNIETKSNALDIIFQTDLTGQKKGWKLRYHGDPMPCPKEDTPNSVWEPAKAKYVFRDVVQITCLDGFEVVEGRVGATSFYSTCQSNGKWSNSKLKCQPVDCGIPESIENGKVEDPESTLFGSVIRYTCEEPYYYMENGGGGEYHCAGNGSWVNEVLGPELPKCVPVCGVPREPFEEKQRIIGGSDADIKNFPWQVFFDNPWAGGALINEYWVLTAAHVVEGNREPTMYVGSTSVQTSRLAKSKMLTPEHVFIHPGWKLLEVPEGRTNFDNDIALVRLKDPVKMGPTVSPICLPGTSSDYNLMDGDLGLISGWGRTEKRDRAVRLKAARLPVAPLRKCKEVKVEKPTADAEAYVFTPNMICAGGEKGMDSCKGDSGGAFAVQDPNDKTKFYAAGLVSWGPQCGTYGLYTRVKNYVDWIMKTMQENSTPRED
- Proteomes:
- UP000005640
Function
- Function:
- C1s B chain is a serine protease that combines with C1q and C1r to form C1, the first component of the classical pathway of the complement system. C1r activates C1s so that it can, in turn, activate C2 and C4.
- Catalytic Activity:
- Cleavage of Arg-|-Ala bond in complement component C4 to form C4a and C4b, and Lys(or Arg)-|-Lys bond in complement component C2 to form C2a and C2b: the 'classical' pathway C3 convertase.
- Kinetics:
- BIOPHYSICOCHEMICAL PROPERTIES: ; Kinetic parameters: KM=12.3 uM for complement component C2 (at 37 degrees Celsius)
- Enzyme Regulation:
- ENZYME REGULATION: Inhibited by SERPING1.
- Active Site:
- ACT_SITE 475 475 Charge relay system.; ACT_SITE 529 529 Charge relay system.; ACT_SITE 632 632 Charge relay system.
- Cross Reference Drug Bank:
- DB00054 DB00051 DB00074 DB00002 DB00005 DB00056 DB00078 DB00075 DB00073 DB00072
- Gene Ontology Go:
- blood microparticle
extracellular exosome
extracellular region
calcium ion binding
identical protein binding
serine-type endopeptidase activity
complement activation
complement activation, classical pathway
innate immune response - Gene Ontology Biological Process:
- complement activation
complement activation, classical pathway
innate immune response - Gene Ontology Molecular Function:
- calcium ion binding
identical protein binding
serine-type endopeptidase activity - Gene Ontology Cellular Component:
- blood microparticle
extracellular exosome
extracellular region - Keywords:
- 3D-structure
Calcium
Complement pathway
Complete proteome
Direct protein sequencing
Disulfide bond
EGF-like domain
Glycoprotein
Hydrolase
Hydroxylation
Immunity
Innate immunity
Metal-binding
Polymorphism
Protease
Reference proteome
Repeat
Serine protease
Signal
Sushi - Interacts With:
- Itself; P00736