CD55

SECTIONS

1 - Domain
2 - Function
3 - Involvement in disease
4 - Post-translational modifications
5 - Sequence similarities
6 - Tissue specificity
7 - Cellular localization
8 - Alternative names
9 - Database links
10 - Target type
11 - Primary research area
12 - Molecular weight

Domain

The first Sushi domain (SCR1) is not necessary for function. SCR2 and SCR4 provide the proper conformation for the active site on SCR3 (By similarity).

Function

This protein recognizes C4b and C3b fragments that condense with cell-surface hydroxyl or amino groups when nascent C4b and C3b are locally generated during C4 and c3 activation. Interaction of daf with cell-associated C4b and C3b polypeptides interferes with their ability to catalyze the conversion of C2 and factor B to enzymatically active C2a and Bb and thereby prevents the formation of C4b2a and C3bBb, the amplification convertases of the complement cascade (PubMed:7525274). Inhibits complement activation by destabilizing and preventing the formation of C3 and C5 convertases, which prevents complement damage (PubMed:28657829).

(Microbial infection) Acts as a receptor for Coxsackievirus A21, coxsackieviruses B1, B3 and B5.

(Microbial infection) Acts as a receptor for Human enterovirus 70 and D68 (Probable).

(Microbial infection) Acts as a receptor for Human echoviruses 6, 7, 11, 12, 20 and 21.

Involvement in disease

Complement hyperactivation, angiopathic thrombosis, and protein-losing enteropathy

CHAPLE

An autosomal recessive disease characterized by abdominal pain and diarrhea, primary intestinal lymphangiectasia, edema due to hypoproteinemia, malabsorption, and less frequently, bowel inflammation, recurrent infections, and angiopathic thromboembolic disease. Patients' T lymphocytes show increased complement activation causing surface deposition of complement and the generation of soluble C5a.

None

The disease is caused by variants affecting the gene represented in this entry. CHAPLE is caused by biallelic mutations in the CD55 gene.

Post-translational modifications

The Ser/Thr-rich domain is heavily O-glycosylated.

Sequence similarities

Belongs to the receptors of complement activation (RCA) family.

Tissue specificity

Expressed on the plasma membranes of all cell types that are in intimate contact with plasma complement proteins. It is also found on the surfaces of epithelial cells lining extracellular compartments, and variants of the molecule are present in body fluids and in extracellular matrix.