Complement component 1s

C1S
Identifiers
Aliases	C1S, EDSPD2, complement C1s
External IDs	OMIM: 120580; MGI: 3644269; GeneCards: C1S
Available structures
PDB	Ortholog search: PDBe RCSB
List of PDB id codes
	1ELV, 1NZI, 4J1Y, 4LMF, 4LOR, 4LOS, 4LOT
Enzyme activity
Gene location (Human)
Chr.	Chromosome 12 (human)
End	7,071,032 bp
Gene location (Mouse)
Chr.	Chromosome 6 (mouse)
End	124,613,044 bp
RNA expression pattern
	Top expressed in
	pericardium; ; right lobe of liver; ; parietal pleura; ; right ovary; ; gallbladder; ; left ovary; ; gastric mucosa; ; tibial nerve; ; left uterine tube; ; synovial joint;
	Top expressed in
	muscle of thigh; ; morula; ; embryo; ; white adipose tissue; ; bone marrow; ; adrenal gland; ; urinary bladder; ; ovary; ; lens; ; islet of Langerhans;
	More reference expression data
	More reference expression data
Gene ontology
Molecular function	calcium ion binding; peptidase activity; serine-type peptidase activity; protein binding; hydrolase activity; metal ion binding; identical protein binding; serine-type endopeptidase activity;
Cellular component	blood microparticle; extracellular exosome; extracellular region; extracellular space;
Biological process	proteolysis; complement activation, classical pathway; immune system process; innate immune response; complement activation, lectin pathway; complement activation; regulation of complement activation;
	Sources:Amigo / QuickGO
Orthologs
Databases	NCBI: entry; OMA: entry
	716
	317677
	ENSG00000182326
	ENSMUSG00000079343
	P09871
	Q8CFG8
	NM_001734; NM_201442; NM_001346850
	NM_173864
	NP_001333779; NP_001725; NP_958850
	NP_776289
	Wikidata
View/Edit Human	View/Edit Mouse

Complement component 1s (EC 3.4.21.42, C1 esterase, activated complement C1s, complement C overbar 1r, C1s) is a protein involved in the complement system. C1s is part of the C1 complex. In humans, it is encoded by the C1S gene.

C1s cleaves C4 and C2, which eventually leads to the production of the classical pathway C3-convertase.

Endopeptidases: serine proteases/serine endopeptidases (EC 3.4.21)
Digestive enzymes	Enteropeptidase Trypsin Chymotrypsin Elastase Neutrophil Pancreatic
Coagulation	factors: Thrombin Factor VIIa Factor IXa Factor Xa Factor XIa Factor XIIa Kallikrein PSA KLK1 KLK2 KLK3 KLK4 KLK5 KLK6 KLK7 KLK8 KLK9 KLK10 KLK11 KLK12 KLK13 KLK14 KLK15 fibrinolysis: Plasmin Plasminogen activator Tissue-type plasminogen activator Urinary plasminogen activator
Complement system	Factor B Factor D Factor I MASP MASP1 MASP2 C3-convertase
Other immune system	Chymase Granzyme Tryptase Proteinase 3/Myeloblastin
Venombin	Ancrod Batroxobin
Other	Acrosin Prolyl endopeptidase Pronase Proprotein convertases 1 2 Prostasin Reelin Subtilisin/Furin/S1P4 Sedolisin/TPP1 Streptokinase Cathepsin A G

Enzymes
Activity	Active site Binding site Catalytic triad Oxyanion hole Enzyme promiscuity Diffusion-limited enzyme Cofactor Enzyme catalysis
Regulation	Allosteric regulation Cooperativity Enzyme inhibitor Enzyme activator
Classification	EC number Enzyme superfamily Enzyme family List of enzymes
Kinetics	Enzyme kinetics Eadie–Hofstee diagram Hanes–Woolf plot Lineweaver–Burk plot Michaelis–Menten kinetics
Types	EC1 Oxidoreductases (list) EC2 Transferases (list) EC3 Hydrolases (list) EC4 Lyases (list) EC5 Isomerases (list) EC6 Ligases (list) EC7 Translocases (list)

Complement component 1s

See also