C8A

Chr 1p32.2

complement C8 alpha chain

MANE:: ENST00000361249.4

OMIM: 120950 ↗NCBI: 731 ↗Ensembl ↗

Annotations refreshed 1 month ago.

Predicted protein structure

AlphaFold predicted structure

C8A · P07357

v62025-08-01

Predicted Aligned Error matrix for C8A — diagonal shows residue index, colour shows pairwise prediction confidence (lower is better) — Predicted Aligned Error

Mean pLDDT

78.7/ 100

Confident

584 residues

Confidence breakdown

Very high(≥ 90)30%
Confident(70–90)49%
Low(50–70)8%
Very low(< 50)13%

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

Disease associations (Open Targets)

Immunodeficiency due to a late component of complements deficiency
0.69
complement deficiency
0.46
immunodeficiency due to a late component of complement deficiency
0.37
focal epilepsy
0.27
ankylosing spondylitis
0.26
pernicious anemia
0.06
macular degeneration
0.06
bone Paget disease
0.04
dentin dysplasia
0.04
esophageal disorder
0.04

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

Protein function (UniProt)

Complement component C8 alpha chain

Component of the membrane attack complex (MAC), a multiprotein complex activated by the complement cascade, which inserts into a target cell membrane and forms a pore, leading to target cell membrane rupture and cell lysis (PubMed:17872444, PubMed:22832194, PubMed:26841837, PubMed:27052168, PubMed:30552328, PubMed:7440581). The MAC is initiated by proteolytic cleavage of C5 into complement C5b in response to the classical, alternative, lectin and GZMK complement pathways (PubMed:17872444, PubMed:30552328, PubMed:39914456, PubMed:39814882, PubMed:7440581). The complement pathways consist in a cascade of proteins that leads to phagocytosis and breakdown of pathogens and signaling that strengthens the adaptive immune system (PubMed:17872444, PubMed:30552328, PubMed:7440581). C8A, together with C8B and C8G, inserts into the target membrane, but does not form pores by itself (PubMed:17872444, PubMed:30552328). During MAC assembly, associates with C5b, C6 and C7 to form the C5b8 intermediate complex that inserts into the target membrane and traverses the bilayer increasing membrane rigidity (PubMed:30552328, PubMed:6833260)