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| | ==Crystallographic structure of human C1q globular heads complexed to phosphatidyl-serine== | | ==Crystallographic structure of human C1q globular heads complexed to phosphatidyl-serine== |
| - | <StructureSection load='2jg8' size='340' side='right' caption='[[2jg8]], [[Resolution|resolution]] 2.05Å' scene=''> | + | <StructureSection load='2jg8' size='340' side='right'caption='[[2jg8]], [[Resolution|resolution]] 2.05Å' scene=''> |
| | == Structural highlights == | | == Structural highlights == |
| - | <table><tr><td colspan='2'>[[2jg8]] is a 6 chain structure with sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2JG8 OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=2JG8 FirstGlance]. <br> | + | <table><tr><td colspan='2'>[[2jg8]] is a 6 chain structure with sequence from [https://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2JG8 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=2JG8 FirstGlance]. <br> |
| - | </td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=CA:CALCIUM+ION'>CA</scene>, <scene name='pdbligand=NAG:N-ACETYL-D-GLUCOSAMINE'>NAG</scene>, <scene name='pdbligand=SEP:PHOSPHOSERINE'>SEP</scene></td></tr> | + | </td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.05Å</td></tr> |
| - | <tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat">[[2jg9|2jg9]], [[1pk6|1pk6]]</td></tr>
| + | <tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=CA:CALCIUM+ION'>CA</scene>, <scene name='pdbligand=NAG:N-ACETYL-D-GLUCOSAMINE'>NAG</scene>, <scene name='pdbligand=SEP:PHOSPHOSERINE'>SEP</scene></td></tr> |
| - | <tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=2jg8 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2jg8 OCA], [http://pdbe.org/2jg8 PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=2jg8 RCSB], [http://www.ebi.ac.uk/pdbsum/2jg8 PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=2jg8 ProSAT]</span></td></tr> | + | <tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=2jg8 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2jg8 OCA], [https://pdbe.org/2jg8 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=2jg8 RCSB], [https://www.ebi.ac.uk/pdbsum/2jg8 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=2jg8 ProSAT]</span></td></tr> |
| | </table> | | </table> |
| | == Disease == | | == Disease == |
| - | [[http://www.uniprot.org/uniprot/C1QA_HUMAN C1QA_HUMAN]] Defects in C1QA are a cause of complement component C1q deficiency (C1QD) [MIM:[http://omim.org/entry/613652 613652]]. A rare defect resulting in C1 deficiency and impaired activation of the complement classical pathway. C1 deficiency generally leads to severe immune complex disease with features of systemic lupus erythematosus and glomerulonephritis. [[http://www.uniprot.org/uniprot/C1QC_HUMAN C1QC_HUMAN]] Defects in C1QC are a cause of complement component C1q deficiency (C1QD) [MIM:[http://omim.org/entry/613652 613652]]. A rare defect resulting in C1 deficiency and impaired activation of the complement classical pathway. C1 deficiency generally leads to severe immune complex disease with features of systemic lupus erythematosus and glomerulonephritis.<ref>PMID:8630118</ref> [[http://www.uniprot.org/uniprot/C1QB_HUMAN C1QB_HUMAN]] Defects in C1QB are a cause of complement component C1q deficiency (C1QD) [MIM:[http://omim.org/entry/613652 613652]]. A rare defect resulting in C1 deficiency and impaired activation of the complement classical pathway. C1 deficiency generally leads to severe immune complex disease with features of systemic lupus erythematosus and glomerulonephritis.<ref>PMID:9476130</ref> | + | [https://www.uniprot.org/uniprot/C1QA_HUMAN C1QA_HUMAN] Defects in C1QA are a cause of complement component C1q deficiency (C1QD) [MIM:[https://omim.org/entry/613652 613652]. A rare defect resulting in C1 deficiency and impaired activation of the complement classical pathway. C1 deficiency generally leads to severe immune complex disease with features of systemic lupus erythematosus and glomerulonephritis. |
| | == Function == | | == Function == |
| - | [[http://www.uniprot.org/uniprot/C1QA_HUMAN C1QA_HUMAN]] C1q associates with the proenzymes C1r and C1s to yield C1, the first component of the serum complement system. The collagen-like regions of C1q interact with the Ca(2+)-dependent C1r(2)C1s(2) proenzyme complex, and efficient activation of C1 takes place on interaction of the globular heads of C1q with the Fc regions of IgG or IgM antibody present in immune complexes. [[http://www.uniprot.org/uniprot/C1QC_HUMAN C1QC_HUMAN]] C1q associates with the proenzymes C1r and C1s to yield C1, the first component of the serum complement system. The collagen-like regions of C1q interact with the Ca(2+)-dependent C1r(2)C1s(2) proenzyme complex, and efficient activation of C1 takes place on interaction of the globular heads of C1q with the Fc regions of IgG or IgM antibody present in immune complexes. [[http://www.uniprot.org/uniprot/C1QB_HUMAN C1QB_HUMAN]] C1q associates with the proenzymes C1r and C1s to yield C1, the first component of the serum complement system. The collagen-like regions of C1q interact with the Ca(2+)-dependent C1r(2)C1s(2) proenzyme complex, and efficient activation of C1 takes place on interaction of the globular heads of C1q with the Fc regions of IgG or IgM antibody present in immune complexes. | + | [https://www.uniprot.org/uniprot/C1QA_HUMAN C1QA_HUMAN] C1q associates with the proenzymes C1r and C1s to yield C1, the first component of the serum complement system. The collagen-like regions of C1q interact with the Ca(2+)-dependent C1r(2)C1s(2) proenzyme complex, and efficient activation of C1 takes place on interaction of the globular heads of C1q with the Fc regions of IgG or IgM antibody present in immune complexes. |
| | == Evolutionary Conservation == | | == Evolutionary Conservation == |
| | [[Image:Consurf_key_small.gif|200px|right]] | | [[Image:Consurf_key_small.gif|200px|right]] |
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| | </StructureSection> | | </StructureSection> |
| | [[Category: Homo sapiens]] | | [[Category: Homo sapiens]] |
| - | [[Category: Arlaud, G J]] | + | [[Category: Large Structures]] |
| - | [[Category: Darnault, C]] | + | [[Category: Arlaud GJ]] |
| - | [[Category: Frachet, P]] | + | [[Category: Darnault C]] |
| - | [[Category: Gaboriaud, C]] | + | [[Category: Frachet P]] |
| - | [[Category: Garlatti, V]] | + | [[Category: Gaboriaud C]] |
| - | [[Category: Ghebrehiwet, B]] | + | [[Category: Garlatti V]] |
| - | [[Category: Paidassi, H]] | + | [[Category: Ghebrehiwet B]] |
| - | [[Category: Tacnet-Delorme, P]] | + | [[Category: Paidassi H]] |
| - | [[Category: Apopotosis]]
| + | [[Category: Tacnet-Delorme P]] |
| - | [[Category: Cell surface molecule]]
| + | |
| - | [[Category: Collagen]]
| + | |
| - | [[Category: Complement]]
| + | |
| - | [[Category: Complement pathway]]
| + | |
| - | [[Category: Disease mutation]]
| + | |
| - | [[Category: Glycoprotein]]
| + | |
| - | [[Category: Hydroxylation]]
| + | |
| - | [[Category: Immune response]]
| + | |
| - | [[Category: Immune system]]
| + | |
| - | [[Category: Innate immunity]]
| + | |
| - | [[Category: Phagocytosis]]
| + | |
| - | [[Category: Polymorphism]]
| + | |
| - | [[Category: Pyrrolidone carboxylic acid]]
| + | |
| - | [[Category: Tolerance]]
| + | |
| Structural highlights
Disease
C1QA_HUMAN Defects in C1QA are a cause of complement component C1q deficiency (C1QD) [MIM:613652. A rare defect resulting in C1 deficiency and impaired activation of the complement classical pathway. C1 deficiency generally leads to severe immune complex disease with features of systemic lupus erythematosus and glomerulonephritis.
Function
C1QA_HUMAN C1q associates with the proenzymes C1r and C1s to yield C1, the first component of the serum complement system. The collagen-like regions of C1q interact with the Ca(2+)-dependent C1r(2)C1s(2) proenzyme complex, and efficient activation of C1 takes place on interaction of the globular heads of C1q with the Fc regions of IgG or IgM antibody present in immune complexes.
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
Efficient apoptotic cell clearance is critical for maintenance of tissue homeostasis, and to control the immune responses mediated by phagocytes. Little is known about the molecules that contribute "eat me" signals on the apoptotic cell surface. C1q, the recognition unit of the C1 complex of complement, also senses altered structures from self and is a major actor of immune tolerance. HeLa cells were rendered apoptotic by UV-B treatment and a variety of cellular and molecular approaches were used to investigate the nature of the target(s) recognized by C1q. Using surface plasmon resonance, C1q binding was shown to occur at early stages of apoptosis and to involve recognition of a cell membrane component. C1q binding and phosphatidylserine (PS) exposure, as measured by annexin V labeling, proceeded concomitantly, and annexin V inhibited C1q binding in a dose-dependent manner. As shown by cosedimentation, surface plasmon resonance, and x-ray crystallographic analyses, C1q recognized PS specifically and avidly (K(D) = 3.7-7 x 10(-8) M), through multiple interactions between its globular domain and the phosphoserine group of PS. Confocal microscopy revealed that the majority of the C1q molecules were distributed in membrane patches where they colocalized with PS. In summary, PS is one of the C1q ligands on apoptotic cells, and C1q-PS interaction takes place at early stages of apoptosis, in newly organized membrane patches. Given its versatile recognition properties, these data suggest that C1q has the unique ability to sense different markers which collectively would provide strong eat me signals, thereby allowing efficient apoptotic cell removal.
C1q Binds Phosphatidylserine and Likely Acts as a Multiligand-Bridging Molecule in Apoptotic Cell Recognition.,Paidassi H, Tacnet-Delorme P, Garlatti V, Darnault C, Ghebrehiwet B, Gaboriaud C, Arlaud GJ, Frachet P J Immunol. 2008 Feb 15;180(4):2329-2338. PMID:18250442[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Paidassi H, Tacnet-Delorme P, Garlatti V, Darnault C, Ghebrehiwet B, Gaboriaud C, Arlaud GJ, Frachet P. C1q Binds Phosphatidylserine and Likely Acts as a Multiligand-Bridging Molecule in Apoptotic Cell Recognition. J Immunol. 2008 Feb 15;180(4):2329-2338. PMID:18250442
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