| Structural highlights
Disease
[MCP_HUMAN] Defects in CD46 are a cause of susceptibility to hemolytic uremic syndrome atypical type 2 (AHUS2) [MIM:612922]. An atypical form of hemolytic uremic syndrome. It is a complex genetic disease characterized by microangiopathic hemolytic anemia, thrombocytopenia, renal failure and absence of episodes of enterocolitis and diarrhea. In contrast to typical hemolytic uremic syndrome, atypical forms have a poorer prognosis, with higher death rates and frequent progression to end-stage renal disease. Note=Susceptibility to the development of atypical hemolytic uremic syndrome can be conferred by mutations in various components of or regulatory factors in the complement cascade system. Other genes may play a role in modifying the phenotype. Patients with CD46 mutations seem to have an overall better prognosis compared to patients carrying CFH mutations.[1] [2] [3] [4] [5]
Function
[MCP_HUMAN] Acts as a cofactor for complement factor I, a serine protease which protects autologous cells against complement-mediated injury by cleaving C3b and C4b deposited on host tissue. May be involved in the fusion of the spermatozoa with the oocyte during fertilization. Also acts as a costimulatory factor for T-cells which induces the differentiation of CD4+ into T-regulatory 1 cells. T-regulatory 1 cells suppress immune responses by secreting interleukin-10, and therefore are thought to prevent autoimmunity. A number of viral and bacterial pathogens seem to exploit this property and directly induce an immunosuppressive phenotype in T-cells by binding to CD46.[6] [7]
Evolutionary Conservation
Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.
Publication Abstract from PubMed
Measles virus is a paramyxovirus which, like other members of the family such as respiratory syncytial virus, is a major cause of morbidity and mortality worldwide. The cell surface receptor for measles virus in humans is CD46, a complement cofactor. We report here the crystal structure at 3.1 A resolution of the measles virus-binding fragment of CD46. The structure reveals the architecture and spatial arrangement of two glycosylated short consensus repeats with a pronounced interdomain bend and some flexibility at the domain interface. Amino acids involved in measles virus binding define a large, glycan-free surface that extends from the top of the first to the bottom of the second repeat. The extended virus-binding surface of CD46 differs strikingly from those reported for the human virus receptor proteins CD4 and intercellular cell adhesion molecule-1 (ICAM-1), suggesting that the CD46 structure utilizes a novel mode of virus recognition. A highly hydrophobic and protruding loop at the base of the first repeat bears a critical virus-binding residue, thereby defining an important recognition epitope. Molecules that mimic the conformation of this loop potentially could be effective anti-viral agents by preventing binding of measles virus to CD46.
Crystal structure of two CD46 domains reveals an extended measles virus-binding surface.,Casasnovas JM, Larvie M, Stehle T EMBO J. 1999 Jun 1;18(11):2911-22. PMID:10357804[8]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Noris M, Brioschi S, Caprioli J, Todeschini M, Bresin E, Porrati F, Gamba S, Remuzzi G. Familial haemolytic uraemic syndrome and an MCP mutation. Lancet. 2003 Nov 8;362(9395):1542-7. PMID:14615110 doi:10.1016/S0140-6736(03)14742-3
- ↑ Richards A, Kemp EJ, Liszewski MK, Goodship JA, Lampe AK, Decorte R, Muslumanoglu MH, Kavukcu S, Filler G, Pirson Y, Wen LS, Atkinson JP, Goodship TH. Mutations in human complement regulator, membrane cofactor protein (CD46), predispose to development of familial hemolytic uremic syndrome. Proc Natl Acad Sci U S A. 2003 Oct 28;100(22):12966-71. Epub 2003 Oct 17. PMID:14566051 doi:10.1073/pnas.2135497100
- ↑ Caprioli J, Noris M, Brioschi S, Pianetti G, Castelletti F, Bettinaglio P, Mele C, Bresin E, Cassis L, Gamba S, Porrati F, Bucchioni S, Monteferrante G, Fang CJ, Liszewski MK, Kavanagh D, Atkinson JP, Remuzzi G. Genetics of HUS: the impact of MCP, CFH, and IF mutations on clinical presentation, response to treatment, and outcome. Blood. 2006 Aug 15;108(4):1267-79. Epub 2006 Apr 18. PMID:16621965 doi:10.1182/blood-2005-10-007252
- ↑ Esparza-Gordillo J, Jorge EG, Garrido CA, Carreras L, Lopez-Trascasa M, Sanchez-Corral P, de Cordoba SR. Insights into hemolytic uremic syndrome: segregation of three independent predisposition factors in a large, multiple affected pedigree. Mol Immunol. 2006 Apr;43(11):1769-75. Epub 2006 Jan 18. PMID:16386793 doi:10.1016/j.molimm.2005.11.008
- ↑ Maga TK, Nishimura CJ, Weaver AE, Frees KL, Smith RJ. Mutations in alternative pathway complement proteins in American patients with atypical hemolytic uremic syndrome. Hum Mutat. 2010 Jun;31(6):E1445-60. doi: 10.1002/humu.21256. PMID:20513133 doi:10.1002/humu.21256
- ↑ Astier A, Trescol-Biemont MC, Azocar O, Lamouille B, Rabourdin-Combe C. Cutting edge: CD46, a new costimulatory molecule for T cells, that induces p120CBL and LAT phosphorylation. J Immunol. 2000 Jun 15;164(12):6091-5. PMID:10843656
- ↑ Kemper C, Chan AC, Green JM, Brett KA, Murphy KM, Atkinson JP. Activation of human CD4+ cells with CD3 and CD46 induces a T-regulatory cell 1 phenotype. Nature. 2003 Jan 23;421(6921):388-92. PMID:12540904 doi:10.1038/nature01315
- ↑ Casasnovas JM, Larvie M, Stehle T. Crystal structure of two CD46 domains reveals an extended measles virus-binding surface. EMBO J. 1999 Jun 1;18(11):2911-22. PMID:10357804 doi:10.1093/emboj/18.11.2911
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