The complement decomposition acceleration factor , or CD55 ( Eng.Complement decay-accelerating factor ; DAF) is a membrane protein , an inhibitor of the complement system . Human gene product CD55 . [one]
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| , CR, CROM, DAF, TC, CD55 molecule (Cromer blood group), CHAPLE | |||||||||||||
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Functions
DAF regulates the complement system on the cell surface. It recognizes fragments C4b and C3b formed during the activation of C4 (classical and lectin paths) and C3 (alternative path). The interaction of DAF with cell-bound C4b and C3b blocks the ability to catalyze the conversion of C2 and factor B into active fragments of C2a and Bb and, as a result, prevents the formation of complexes C4b2a and C3bBb, amplification of complement cascades. As a result, this blocks the formation of membrane-attacking complexes (MAC). [2]
It is an antigen of the Cromer blood group system.
Structure
CD55 (DAF) consists of 319 amino acids (after cleavage of the signal peptide and propeptide). It is a glycoprotein with a molecular weight of 70 kDa. It includes 4 Sushi domains, a lipidation site ( glycosylphosphatidylinositol binding, which provides protein anchoring on the cell membrane) and 8 intramolecular disulfide bonds . In addition, it contains one N-glycosylation site .
Tissue specificity
It is widely represented both in hematopoietic cells and in non-hematopoietic cells.
Pathology
Paroxysmal nocturnal hemoglobinuria
Since DAF is anchored on the cell membrane due to glycosylphosphatidylinositol, protein expression is reduced by mutations that lower the level of this lipid, such as paroxysmal nocturnal hemoglobinuria . In this case, red blood cells with a low level of DAF undergo complement-mediated hemolysis. [3]
Viral infection
DAF is a receptor for certain Coxsackie viruses and other enteroviruses that use protein to enter the cell. [four]
Notes
- ↑ Medof ME, Lublin DM, Holers VM, Ayers DJ, Getty RR, Leykam JF, Atkinson JP, Tykocinski ML Cloning and characterization of cDNAs encoding the complete sequence of decay-accelerating factor of human complement (English) // Proceedings of the National Academy of Sciences of the United States of America : journal. - 1987 .-- April ( vol. 84 , no. 7 ). - P. 2007—2011 . - DOI : 10.1073 / pnas . 84.7.2007 . - PMID 2436222 .
- ↑ genecards.org
- ↑ Parker C., Omine M., Richards S., et al. Diagnosis and management of paroxysmal nocturnal hemoglobinuria (Eng.) // Blood : journal. - American Society of Hematology 2005. - Vol. 106 , no. 12 . - P. 3699-3709 . - DOI : 10.1182 / blood-2005-04-1717 . - PMID 16051736 .
- ↑ Karnauchow TM, Tolson DL, Harrison BA, Altman E., Lublin DM, Dimock K. The HeLa cell receptor for enterovirus 70 is decay-accelerating factor (CD55 ) // J. Virol. : journal. - 1996 .-- August ( vol. 70 , no. 8 ). - P. 5143-5152 . - PMID 8764022 .
Literature
- Selinka HC, Wolde A., Sauter M., et al. Virus-receptor interactions of coxsackie B viruses and their putative influence on cardiotropism. (English) // Med. Microbiol. Immunol. : journal. - 2004. - Vol. 193 , no. 2-3 . - P. 127-131 . - DOI : 10.1007 / s00430-003-0193-y . - PMID 12920584 .
- Mikesch JH, Schier K., Roetger A., et al. The expression and action of decay-accelerating factor (CD55) in human malignancies and cancer therapy. (English) // Cell. Oncol. : journal. - 2007. - Vol. 28 , no. 5-6 . - P. 223-232 . - PMID 17167176 .