View source for 4hw5

==Crystal Structure of the Human C3a anaphylatoxin==
<StructureSection load='4hw5' size='340' side='right' caption='[[4hw5]], [[Resolution|resolution]] 2.25&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[4hw5]] is a 2 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=4HW5 OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=4HW5 FirstGlance]. <br>
</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=SO4:SULFATE+ION'>SO4</scene></td></tr>
<tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat">[[4hwj|4hwj]]</td></tr>
<tr id='gene'><td class="sblockLbl"><b>[[Gene|Gene:]]</b></td><td class="sblockDat">C3, CPAMD1 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=9606 Homo sapiens])</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=4hw5 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4hw5 OCA], [http://www.rcsb.org/pdb/explore.do?structureId=4hw5 RCSB], [http://www.ebi.ac.uk/pdbsum/4hw5 PDBsum]</span></td></tr>
</table>
== Disease ==
[[http://www.uniprot.org/uniprot/CO3_HUMAN CO3_HUMAN]] Defects in C3 are the cause of complement component 3 deficiency (C3D) [MIM:[http://omim.org/entry/613779 613779]]. A rare defect of the complement classical pathway. Patients develop recurrent, severe, pyogenic infections because of ineffective opsonization of pathogens. Some patients may also develop autoimmune disorders, such as arthralgia and vasculitic rashes, lupus-like syndrome and membranoproliferative glomerulonephritis.<ref>PMID:19913840</ref> <ref>PMID:9596584</ref> <ref>PMID:11387479</ref> <ref>PMID:15713468</ref> <ref>PMID:7961791</ref> [:]  Genetic variation in C3 is associated with susceptibility to age-related macular degeneration type 9 (ARMD9) [MIM:[http://omim.org/entry/611378 611378]]. ARMD is a multifactorial eye disease and the most common cause of irreversible vision loss in the developed world. In most patients, the disease is manifest as ophthalmoscopically visible yellowish accumulations of protein and lipid that lie beneath the retinal pigment epithelium and within an elastin-containing structure known as Bruch membrane.<ref>PMID:19913840</ref> <ref>PMID:17634448</ref>   Defects in C3 are a cause of susceptibility to hemolytic uremic syndrome atypical type 5 (AHUS5) [MIM:[http://omim.org/entry/612925 612925]]. 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.<ref>PMID:19913840</ref> <ref>PMID:18796626</ref> <ref>PMID:20513133</ref>   Note=Increased levels of C3 and its cleavage product ASP, are associated with obesity, diabetes and coronary heart disease. Short-term endurance training reduces baseline ASP levels and subsequently fat storage.<ref>PMID:19913840</ref>  
== Function ==
[[http://www.uniprot.org/uniprot/CO3_HUMAN CO3_HUMAN]] C3 plays a central role in the activation of the complement system. Its processing by C3 convertase is the central reaction in both classical and alternative complement pathways. After activation C3b can bind covalently, via its reactive thioester, to cell surface carbohydrates or immune aggregates.<ref>PMID:8376604</ref> <ref>PMID:2909530</ref> <ref>PMID:9059512</ref> <ref>PMID:9555951</ref> <ref>PMID:10432298</ref> <ref>PMID:15833747</ref> <ref>PMID:16333141</ref> <ref>PMID:19615750</ref>   Derived from proteolytic degradation of complement C3, C3a anaphylatoxin is a mediator of local inflammatory process. It induces the contraction of smooth muscle, increases vascular permeability and causes histamine release from mast cells and basophilic leukocytes.<ref>PMID:8376604</ref> <ref>PMID:2909530</ref> <ref>PMID:9059512</ref> <ref>PMID:9555951</ref> <ref>PMID:10432298</ref> <ref>PMID:15833747</ref> <ref>PMID:16333141</ref> <ref>PMID:19615750</ref>   Acylation stimulating protein (ASP): adipogenic hormone that stimulates triglyceride (TG) synthesis and glucose transport in adipocytes, regulating fat storage and playing a role in postprandial TG clearance. Appears to stimulate TG synthesis via activation of the PLC, MAPK and AKT signaling pathways. Ligand for GPR77. Promotes the phosphorylation, ARRB2-mediated internalization and recycling of GPR77.<ref>PMID:8376604</ref> <ref>PMID:2909530</ref> <ref>PMID:9059512</ref> <ref>PMID:9555951</ref> <ref>PMID:10432298</ref> <ref>PMID:15833747</ref> <ref>PMID:16333141</ref> <ref>PMID:19615750</ref>  
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Complement is a part of innate immunity that has a critical role in the protection against microbial infections, bridges the innate with the adaptive immunity and initiates inflammation. Activation of the complement, by specific recognition of molecular patterns presented by an activator, e.g. a pathogen cell, in the classical and lectin pathways or spontaneously in the alternative pathway, leads to the opsonization of the activator and the production of pro-inflammatory molecules such as the C3a anaphylatoxin. The biological function of this anaphylatoxin is regulated by carboxypeptidase B, a plasma protease that cleaves off the C-terminal arginine yielding C3a desArg, an inactive form. While functional assays demonstrate strikingly different physiological effects between C3a and C3a desArg, no structural information is available on the possible conformational differences between the two proteins. Here, we report a novel and simple expression and purification protocol for recombinant human C3a and C3a desArg anaphylatoxins, as well as their crystal structures at 2.3 and 2.6 A respectively. Structural analysis revealed no significant conformational differences between the two anaphylatoxins in contrast to what has been reported for C5a and C5a desArg. We compare the structures of different anaphylatoxins and discuss the relevance of their observed conformations to complement activation and binding of the anaphylatoxins to their cognate receptors.

Human C3a and C3a desArg anaphylatoxins have conserved structures, in contrast to C5a and C5a desArg.,Bajic G, Yatime L, Klos A, Andersen GR Protein Sci. 2012 Nov 26. doi: 10.1002/pro.2200. PMID:23184394<ref>PMID:23184394</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>

==See Also==
*[[Complement C3|Complement C3]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Homo sapiens]]
[[Category: Andersen, G R]]
[[Category: Bajic, G]]
[[Category: Yatime, L]]
[[Category: Anaphylatoxin]]
[[Category: C5a]]
[[Category: C5a desarg]]
[[Category: Complement system]]
[[Category: Four-helix-bundle]]
[[Category: Immune system]]
[[Category: Inflammation]]
[[Category: Innate immunity]]