C1QC

Chr 1p36.12

complement C1q C chain

MANE:: ENST00000374640.9

OMIM: 120575 ↗NCBI: 714 ↗Ensembl ↗

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Predicted protein structure

AlphaFold predicted structure

C1QC · P02747

v62025-08-01

Predicted Aligned Error matrix for C1QC — diagonal shows residue index, colour shows pairwise prediction confidence (lower is better) — Predicted Aligned Error

Mean pLDDT

80.6/ 100

Confident

245 residues

Confidence breakdown

Very high(≥ 90)48%
Confident(70–90)13%
Low(50–70)36%
Very low(< 50)4%

Open interactive 3D viewer

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

Clinical relevance (Genomics England PanelApp)

Diagnostic Grade (Green)

COVID-19 research
BIALLELIC, autosomal or pseudoautosomal
Primary immunodeficiency or monogenic inflammatory bowel disease
BIALLELIC, autosomal or pseudoautosomal
Intellectual disability
BIALLELIC, autosomal or pseudoautosomal

Disease associations (Open Targets)

immunodeficiency due to a classical component pathway complement deficiency
0.62
C1Q deficiency
0.60
neurodegenerative disease
0.54
complement deficiency
0.46
C1Q deficiency 1
0.46
C1Q deficiency 3
0.45
placenta praevia
0.32
hereditary disease
0.19
smoking initiation
0.19
tuberculosis
0.08

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

Protein function (UniProt)

Complement C1q subcomponent subunit C

Core 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:12847249, PubMed:19006321, PubMed:24626930, PubMed:29449492, PubMed:3258649, PubMed:34155115, PubMed:6249812, PubMed:6776418). The classical complement pathway is initiated by the C1Q subcomplex of the C1 complex, which specifically binds IgG or IgM immunoglobulins complexed with antigens, forming antigen-antibody complexes on the surface of pathogens: C1QA, together with C1QB and C1QC, specifically recognizes and binds the Fc regions of IgG or IgM via its C1q domain (PubMed:12847249, PubMed:19006321, PubMed:24626930, PubMed:29449492, PubMed:3258649, PubMed:6776418). Immunoglobulin-binding activates the proenzyme C1R, which cleaves C1S, initiating the proteolytic cascade of the complement system (PubMed:29449492). The C1Q subcomplex is activated by a hexamer of IgG complexed with antigens, while it is activated by a pentameric IgM (PubMed:19706439, PubMed:24626930, PubMed:29449492). The C1Q subcomplex also recognizes and binds phosphatidylserine exposed on the surface of cells undergoing programmed cell death, possibly promoting activation of the complement system (PubMed:18250442)