CD55 (Complement Decay-Accelerating Factor) Gene
A key regulator of the complement system with implications in hematologic disorders, infections, and cancer.
Gene Information Card
| Symbol | CD55 |
|---|---|
| Full Name | CD55 molecule (Cromer blood group) |
| Gene Type | Protein coding |
| Chromosomal Location | 1q32.2 |
| NCBI Gene ID | 1604 ncbi.nlm.nih.gov/gene/1604 |
| Ensembl ID | ENSG00000196352 |
| UniProt ID | P08174 |
| OMIM ID | 125240 |
| HGNC ID | 2665 |
| Aliases | DAF, CR, CROM, TC |
Description
The CD55 gene encodes complement decay-accelerating factor (DAF), a glycosylphosphatidylinositol (GPI)-anchored membrane protein that protects host cells from complement-mediated damage by accelerating the decay of C3 and C5 convertases. It is widely expressed on cells exposed to complement, including blood cells and endothelial cells. CD55 also serves as a receptor for certain viruses and bacteria, and its deficiency is linked to paroxysmal nocturnal hemoglobinuria (PNH) and CHAPLE syndrome.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Paroxysmal Nocturnal Hemoglobinuria (PNH) | Somatic mutations in PIGA lead to loss of GPI-anchored proteins including CD55 and CD59 on hematopoietic cells, causing complement-mediated hemolysis. | ClinVar, OMIM |
| CHAPLE syndrome (CD55 deficiency with hyperactivation of complement, angiopathic thrombosis, and protein-losing enteropathy) | Biallelic loss-of-function mutations in CD55 result in unregulated complement activation on intestinal epithelium, leading to protein-losing enteropathy and thrombosis. | OMIM, PubMed |
| Cromer blood group incompatibility | Polymorphisms in CD55 define the Cromer blood group system; antibodies against CD55 can cause transfusion reactions. | UniProt, HGNC |
| Infections (e.g., Enterovirus, Escherichia coli) | CD55 acts as a receptor for several pathogens; variations may influence susceptibility. | PubMed |
| Cancer (various) | CD55 overexpression on tumor cells inhibits complement-mediated lysis, contributing to immune evasion. | COSMIC, PubMed |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Blood | High | High |
| Spleen | High | High |
| Lung | Medium | Medium |
| Liver | Medium | Medium |
| Kidney | Medium | Medium |
| Gastrointestinal tract | Medium | Medium |
| Brain | Low | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| K562 (leukemia) | High | High expression |
| A549 (lung carcinoma) | Medium | Moderate expression |
| HeLa (cervical carcinoma) | Medium | Moderate expression |
| HepG2 (hepatocellular carcinoma) | Medium | Moderate expression |
| MCF7 (breast carcinoma) | Low | Low expression |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.167A>G (p.Tyr56Cys) | Missense | Rare | Impairs complement regulation; associated with CHAPLE syndrome |
| c.286G>A (p.Gly96Arg) | Missense | Rare | Loss of function; complement dysregulation |
| c.449T>C (p.Leu150Pro) | Missense | Rare | Affects protein stability; CHAPLE syndrome |
| c.596C>T (p.Pro199Leu) | Missense | Rare | Reduced surface expression; CHAPLE syndrome |
| c.679G>A (p.Gly227Arg) | Missense | Rare | Loss of function; CHAPLE syndrome |
Mutation functional classification
Loss of Function (LOF)
Biallelic loss-of-function mutations in CD55 cause CHAPLE syndrome, characterized by complement hyperactivation, angiopathic thrombosis, and protein-losing enteropathy.
Gain of Function (GOF)
No gain-of-function mutations are documented; CD55 overexpression in tumors is often due to transcriptional upregulation, not mutation.
Dominant Negative (DN)
No dominant-negative effects reported; CD55 mutations are typically recessive.
View complete mutation data：
Gene Ontology (GO)
| • complement binding | • complement receptor activity |
| • protein binding | • cell surface |
| • extracellular exosome | • membrane |
| • anchored component of membrane | • regulation of complement activation |
| • innate immune response | • cell adhesion |
Pathways
• Complement cascade
• Immune system
• Innate Immune System
Protein Summary
CD55 is a 70 kDa GPI-anchored glycoprotein composed of four short consensus repeats (SCRs), a heavily O-glycosylated serine/threonine-rich region, and a GPI anchor. It inhibits complement by binding to C3b and C4b, accelerating the decay of C3/C5 convertases. It is widely expressed on erythrocytes, leukocytes, platelets, and endothelial cells. CD55 also interacts with pathogens and is involved in T-cell co-stimulation. Its deficiency leads to complement-mediated hemolysis (PNH) or intestinal disease (CHAPLE syndrome).
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| CD55 Knockout HEK293 Cell Line | EDJ-KQ3223 | Human | 1604 | Details Get a Quote |
| CD55 Knockout A-549 Cell Line | EDJ-KQ24720 | Human | 1604 | Details Get a Quote |
| CD55 Knockout HCT 116 Cell Line | EDJ-KQ24721 | Human | 1604 | Details Get a Quote |
| CD55 Knockout HeLa Cell Line | EDJ-KQ24722 | Human | 1604 | Details Get a Quote |
| CD46 and CD55 and CD59 Knockout HEK293 Cell Line | EDC08362 | Human | 4179 and 1604 and 966 | Details Get a Quote |
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