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==Fab fragment of 3D6 in complex with amyloid beta 1-40==
<StructureSection load='4ong' size='340' side='right'caption='[[4ong]], [[Resolution|resolution]] 2.20&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[4ong]] is a 3 chain structure with sequence from [https://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens] and [https://en.wikipedia.org/wiki/Mus_musculus Mus musculus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4ONG OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=4ONG FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.2&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=CL:CHLORIDE+ION'>CL</scene>, <scene name='pdbligand=IMD:IMIDAZOLE'>IMD</scene>, <scene name='pdbligand=ZN:ZINC+ION'>ZN</scene></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=4ong FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4ong OCA], [https://pdbe.org/4ong PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=4ong RCSB], [https://www.ebi.ac.uk/pdbsum/4ong PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=4ong ProSAT]</span></td></tr>
</table>
== Disease ==
[https://www.uniprot.org/uniprot/A4_HUMAN A4_HUMAN] Defects in APP are the cause of Alzheimer disease type 1 (AD1) [MIM:[https://omim.org/entry/104300 104300]. AD1 is a familial early-onset form of Alzheimer disease. It can be associated with cerebral amyloid angiopathy. Alzheimer disease is a neurodegenerative disorder characterized by progressive dementia, loss of cognitive abilities, and deposition of fibrillar amyloid proteins as intraneuronal neurofibrillary tangles, extracellular amyloid plaques and vascular amyloid deposits. The major constituent of these plaques is the neurotoxic amyloid-beta-APP 40-42 peptide (s), derived proteolytically from the transmembrane precursor protein APP by sequential secretase processing. The cytotoxic C-terminal fragments (CTFs) and the caspase-cleaved products such as C31 derived from APP, are also implicated in neuronal death.<ref>PMID:8476439</ref> <ref>PMID:15201367</ref> <ref>PMID:1671712</ref> <ref>PMID:1908231</ref> <ref>PMID:1678058</ref> <ref>PMID:1944558</ref> <ref>PMID:1925564</ref> <ref>PMID:1415269</ref> <ref>PMID:1303239</ref> <ref>PMID:1302033</ref> <ref>PMID:1303275</ref> <ref>PMID:8267572</ref> <ref>PMID:8290042</ref> <ref>PMID:8577393</ref> <ref>PMID:9328472</ref> <ref>PMID:9754958</ref> <ref>PMID:10097173</ref> <ref>PMID:10631141</ref> <ref>PMID:10665499</ref> <ref>PMID:10867787</ref> <ref>PMID:11063718</ref> <ref>PMID:11311152</ref> <ref>PMID:11528419</ref> <ref>PMID:12034808</ref> <ref>PMID:15365148</ref> <ref>PMID:15668448</ref>   Defects in APP are the cause of cerebral amyloid angiopathy APP-related (CAA-APP) [MIM:[https://omim.org/entry/605714 605714]. A hereditary localized amyloidosis due to amyloid-beta A4 peptide(s) deposition in the cerebral vessels. The principal clinical characteristics are recurrent cerebral and cerebellar hemorrhages, recurrent strokes, cerebral ischemia, cerebral infarction, and progressive mental deterioration. Patients develop cerebral hemorrhage because of the severe cerebral amyloid angiopathy. Parenchymal amyloid deposits are rare and largely in the form of pre-amyloid lesions or diffuse plaque-like structures. They are Congo red negative and lack the dense amyloid cores commonly present in Alzheimer disease. Some affected individuals manifest progressive aphasic dementia, leukoencephalopathy, and occipital calcifications.<ref>PMID:10821838</ref> <ref>PMID:2111584</ref> <ref>PMID:11409420</ref> <ref>PMID:12654973</ref> <ref>PMID:16178030</ref> 
== Function ==
[https://www.uniprot.org/uniprot/A4_HUMAN A4_HUMAN] Functions as a cell surface receptor and performs physiological functions on the surface of neurons relevant to neurite growth, neuronal adhesion and axonogenesis. Involved in cell mobility and transcription regulation through protein-protein interactions. Can promote transcription activation through binding to APBB1-KAT5 and inhibits Notch signaling through interaction with Numb. Couples to apoptosis-inducing pathways such as those mediated by G(O) and JIP. Inhibits G(o) alpha ATPase activity (By similarity). Acts as a kinesin I membrane receptor, mediating the axonal transport of beta-secretase and presenilin 1. Involved in copper homeostasis/oxidative stress through copper ion reduction. In vitro, copper-metallated APP induces neuronal death directly or is potentiated through Cu(2+)-mediated low-density lipoprotein oxidation. Can regulate neurite outgrowth through binding to components of the extracellular matrix such as heparin and collagen I and IV. The splice isoforms that contain the BPTI domain possess protease inhibitor activity. Induces a AGER-dependent pathway that involves activation of p38 MAPK, resulting in internalization of amyloid-beta peptide and leading to mitochondrial dysfunction in cultured cortical neurons. Provides Cu(2+) ions for GPC1 which are required for release of nitric oxide (NO) and subsequent degradation of the heparan sulfate chains on GPC1.<ref>PMID:9168929</ref> <ref>PMID:11544248</ref> <ref>PMID:11943163</ref> <ref>PMID:19225519</ref> <ref>PMID:19901339</ref>   Beta-amyloid peptides are lipophilic metal chelators with metal-reducing activity. Bind transient metals such as copper, zinc and iron. In vitro, can reduce Cu(2+) and Fe(3+) to Cu(+) and Fe(2+), respectively. Beta-amyloid 42 is a more effective reductant than beta-amyloid 40. Beta-amyloid peptides bind to lipoproteins and apolipoproteins E and J in the CSF and to HDL particles in plasma, inhibiting metal-catalyzed oxidation of lipoproteins. Beta-APP42 may activate mononuclear phagocytes in the brain and elicit inflammatory responses. Promotes both tau aggregation and TPK II-mediated phosphorylation. Interaction with Also bind GPC1 in lipid rafts.<ref>PMID:9168929</ref> <ref>PMID:11544248</ref> <ref>PMID:11943163</ref> <ref>PMID:19225519</ref> <ref>PMID:19901339</ref>   Appicans elicit adhesion of neural cells to the extracellular matrix and may regulate neurite outgrowth in the brain (By similarity).<ref>PMID:9168929</ref> <ref>PMID:11544248</ref> <ref>PMID:11943163</ref> <ref>PMID:19225519</ref> <ref>PMID:19901339</ref>   The gamma-CTF peptides as well as the caspase-cleaved peptides, including C31, are potent enhancers of neuronal apoptosis.<ref>PMID:9168929</ref> <ref>PMID:11544248</ref> <ref>PMID:11943163</ref> <ref>PMID:19225519</ref> <ref>PMID:19901339</ref>   N-APP binds TNFRSF21 triggering caspase activation and degeneration of both neuronal cell bodies (via caspase-3) and axons (via caspase-6).<ref>PMID:9168929</ref> <ref>PMID:11544248</ref> <ref>PMID:11943163</ref> <ref>PMID:19225519</ref> <ref>PMID:19901339</ref> 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
INTRODUCTION: Immunotherapy targeting amyloid-beta peptide is under active clinical investigation for treatment of Alzheimer's disease (AD). Among the hypotheses being investigated for impact on clinical outcome are the preferred epitope or conformation of amyloid-beta to target for treatment, and the mechanism of action underlying immunotherapy. Bapineuzumab (humanized 3D6), a neo-epitope specific antibody recognizing amyloid-beta1-5 with strong preference for an exposed Asp residue at the N-terminus of the peptide, has undergone advanced clinical testing for treatment of AD. METHODS: To gain further insight into the epitope conformation, we interrogated structural details of amino-terminal epitopes in amyloid-beta using x-ray crystallography of 3D6Fab:amyloid-beta complexes. Humanization of 3D6 was carried out using standard procedures integrating recombinant methods, sequence informatics, and homology modeling predictions to identify important mouse framework residues for retention in the finished humanized product. RESULTS: Here we report the crystal structure of a recombinant Fab fragment of 3D6 in complex with amyloid-beta1-7 solved at 2.0 A resolution. The N-terminus of amyloid-beta is bound to 3D6 as a 310 helix. The amino-terminal Asp residue is buried deepest in the antibody binding pocket, with the Cbeta atom of residue 6 visible at the entrance to the binding pocket near the surface of the antibody. We further evaluate homology model based predictions used to guide humanization of 3D6 to bapineuzumab, with actual structure of the Fab. The structure of the Fab:amyloid-beta complex validates design of the humanized antibody, and confirms the amyloid-beta epitope recognized by 3D6 as previously mapped by ELISA. CONCLUSIONS: The conformation of amyloid-beta antigen recognized by 3D6 is novel and distinct from other antibodies recognizing N-terminal epitopes. Our result provides the first report demonstrating structural conservation of antigen contact residues, and conformation of antigen recognized, between the parent murine antibody and its humanized version.

Crystal structure reveals conservation of amyloid-beta conformation recognized by 3D6 following humanization to bapineuzumab.,Feinberg H, Saldanha JW, Diep L, Goel A, Widom A, Veldman GM, Weis WI, Schenk D, Basi GS Alzheimers Res Ther. 2014 Jun 2;6(3):31. doi: 10.1186/alzrt261. eCollection 2014. PMID:25024748<ref>PMID:25024748</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 4ong" style="background-color:#fffaf0;"></div>

==See Also==
*[[Antibody 3D structures|Antibody 3D structures]]
*[[3D structures of non-human antibody|3D structures of non-human antibody]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Homo sapiens]]
[[Category: Large Structures]]
[[Category: Mus musculus]]
[[Category: Basi GS]]
[[Category: Diep L]]
[[Category: Feinberg H]]
[[Category: Goel A]]
[[Category: Saldanha JW]]
[[Category: Schenk D]]
[[Category: Veldman GM]]
[[Category: Weis WI]]
[[Category: Widom A]]