C1S

Chr 12p13.31

complement C1s

MANE:: ENST00000360817.10

OMIM: 120580 ↗NCBI: 716 ↗Ensembl ↗

Annotations refreshed 9 hours ago.

Predicted protein structure

AlphaFold predicted structure

C1S · P09871

v62025-08-01

Predicted Aligned Error matrix for C1S — diagonal shows residue index, colour shows pairwise prediction confidence (lower is better) — Predicted Aligned Error

Mean pLDDT

87.9/ 100

Confident

688 residues

Confidence breakdown

Very high(≥ 90)66%
Confident(70–90)25%
Low(50–70)6%
Very low(< 50)2%

Open interactive 3D viewer

AlphaFold (Jumper et al., 2021) · CC BY 4.0

Clinical relevance (Genomics England PanelApp)

Diagnostic Grade (Green)

COVID-19 research
BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Ehlers Danlos syndrome with a likely monogenic cause
MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Primary immunodeficiency or monogenic inflammatory bowel disease
BIALLELIC, autosomal or pseudoautosomal

Disease associations (Open Targets)

Ehlers-Danlos syndrome, periodontal type 2
0.68
complement component C1s deficiency
0.66
Ehlers-Danlos syndrome, periodontitis type
0.56
hereditary angioedema
0.54
coronary artery disorder
0.49
cold agglutinin disease
0.49
systemic lupus erythematosus
0.48
autoimmune hemolytic anemia
0.46
complement deficiency
0.46
immunodeficiency due to a classical component pathway complement deficiency
0.37

Score is the Open Targets composite evidence score (0-1). Higher = stronger gene-disease association.

Protein function (UniProt)

Complement C1s subcomponent

Component of the complement C1 complex, a multiprotein complex that initiates the classical pathway of the complement system, a cascade of proteins that leads to phagocytosis and breakdown of pathogens and signaling that strengthens the adaptive immune system (PubMed:11445589, PubMed:16169853, PubMed:417728, PubMed:467643, PubMed:6271784, PubMed:6282646, PubMed:6319179, PubMed:70787, PubMed:9422791). C1S is activated following association of the C1 complex with immunoglobulins (IgG or IgM) complexed with antigens to form antigen-antibody complexes on the surface of pathogens (PubMed:34155115). C1S is cleaved and activated by C1R to generate C1s subcomponent heavy and light chains (PubMed:11445589, PubMed:6271784). C1s subcomponent light chain then cleaves and activates C2 and C4, the next components of the classical complement pathway (PubMed:16169853, PubMed:467643, PubMed:6282646, PubMed:6319179, PubMed:6906228, PubMed:70787, PubMed:9422791)