Alt. symbols: DAF | CR | TC | CROM

Approved name: CD55 molecule (Cromer blood group)
Alt. names: decay accelerating factor for complement (CD55, Cromer blood group system), CD55 molecule, decay accelerating factor for complement (Cromer blood group)

Location: 1q32.2: 207321519 - 207386804 (+)
Gene type: protein_coding, 23 transcripts.

Scores: LoFtool: 0.997000 | pLI: 0.00000025 | LOEUF: 1.273

HGNC: 2665

NCBI: 1604, RefSeq: NG_007465.1

Ensembl: ENSG00000196352.18

LRG_127 | Status: public

OMIM: 125240

Expression | ProteinAtlas

CD55 encodes DAF, an important membrane regulatory factor for protecting host tissues from attack by autologous complement proteins. Specifically, DAF inhibits the complement cascade at the level of the critical C3 convertase step. Its interactions 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). DAF exists as a major 70-kD membrane-bound isoform and a few other soluble and membrane-bound isoforms generated by alternative splicing. The former is widely distributed on all blood cells and on endothelial and epithelial tissues. DAF also serves as a receptor for certain pathogens, including E. coli and certain enteroviruses. Additionally, variation in DAF forms the basis of the Cromer blood group system (PMID: 21214297).

Biallelic frameshift, nonsense, missense and splice site mutations in CD55 cause CHAPLE (complement hyperactivation, angiopathic thrombosis, and protein-losing enteropathy) [OMIM: 226300]. This autosomal recessive condition is characterized by abdominal pain and diarrhea, primary intestinal lymphangiectasia, hypoproteinemic edema, and malabsorption. Additional clinical findings may include bowel inflammation, recurrent infections associated with hypogammaglobulinemia, and/or angiopathic thromboe mbolic disease. Patient T cells show increased complement activation, causing surface deposition of complement and generating soluble C5a (PMID: 28657829). [Load More]