C1S
Available structures PDB Ortholog search: PDBe RCSB List of PDB id codes 1ELV, 1NZI, 4J1Y, 4LMF, 4LOR, 4LOS, 4LOT
Identifiers
Aliases	C1S, EDSPD2, complement C1s
External IDs	OMIM: 120580 MGI: 3644269 HomoloGene: 1314 GeneCards: C1S
EC number	3.4.21.42
Gene location (Human) Chr. Chromosome 12 (human)[1] Band 12p13.31 Start 6,988,259 bp[1] End 7,071,032 bp[1]
Gene location (Mouse) Chr. Chromosome 6 (mouse)[2] Band 6|6 F2 Start 124,601,584 bp[2] End 124,613,044 bp[2]
RNA expression pattern Bgee Human Mouse (ortholog) Top expressed in pericardium right lobe of liver parietal pleura gallbladder gastric mucosa tibial nerve left uterine tube synovial joint canal of the cervix right coronary artery Top expressed in morula white adipose tissue bone marrow adrenal gland urinary bladder ovary lens islet of Langerhans superior frontal gyrus spleen More reference expression data BioGPS 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 Species Human Mouse Entrez 716 317677 Ensembl ENSG00000182326 ENSMUSG00000079343 UniProt P09871 Q8CFG8 RefSeq (mRNA) NM_001734 NM_201442 NM_001346850 NM_173864 RefSeq (protein) NP_001333779 NP_001725 NP_958850 NP_776289 Location (UCSC) Chr 12: 6.99 – 7.07 Mb Chr 6: 124.6 – 124.61 Mb PubMed search [3] [4]
Wikidata
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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.^[5][6][7][8] In humans, it is encoded by the C1S gene.^[9]

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