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==Crystal structure of XIAP-BIR2 domain with ATAA bound==
<StructureSection load='4j45' size='340' side='right'caption='[[4j45]], [[Resolution|resolution]] 1.48&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[4j45]] is a 3 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=4J45 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=4J45 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]] 1.48&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><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=4j45 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4j45 OCA], [https://pdbe.org/4j45 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=4j45 RCSB], [https://www.ebi.ac.uk/pdbsum/4j45 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=4j45 ProSAT]</span></td></tr>
</table>
== Disease ==
[https://www.uniprot.org/uniprot/XIAP_HUMAN XIAP_HUMAN] Defects in XIAP are the cause of lymphoproliferative syndrome X-linked type 2 (XLP2) [MIM:[https://omim.org/entry/300635 300635]. XLP is a rare immunodeficiency characterized by extreme susceptibility to infection with Epstein-Barr virus (EBV). Symptoms include severe or fatal mononucleosis, acquired hypogammaglobulinemia, pancytopenia and malignant lymphoma.<ref>PMID:17080092</ref> 
== Function ==
[https://www.uniprot.org/uniprot/XIAP_HUMAN XIAP_HUMAN] Multi-functional protein which regulates not only caspases and apoptosis, but also modulates inflammatory signaling and immunity, copper homeostasis, mitogenic kinase signaling, cell proliferation, as well as cell invasion and metastasis. Acts as a direct caspase inhibitor. Directly bind to the active site pocket of CASP3 and CASP7 and obstructs substrate entry. Inactivates CASP9 by keeping it in a monomeric, inactive state. Acts as an E3 ubiquitin-protein ligase regulating NF-kappa-B signaling and the target proteins for its E3 ubiquitin-protein ligase activity include: RIPK1, CASP3, CASP7, CASP8, CASP9, MAP3K2/MEKK2, DIABLO/SMAC, AIFM1, CCS and BIRC5/survivin. Ubiquitinion of CCS leads to enhancement of its chaperone activity toward its physiologic target, SOD1, rather than proteasomal degradation. Ubiquitinion of MAP3K2/MEKK2 and AIFM1 does not lead to proteasomal degradation. Plays a role in copper homeostasis by ubiquitinationg COMMD1 and promoting its proteasomal degradation. Can also function as E3 ubiquitin-protein ligase of the NEDD8 conjugation pathway, targeting effector caspases for neddylation and inactivation. Regulates the BMP signaling pathway and the SMAD and MAP3K7/TAK1 dependent pathways leading to NF-kappa-B and JNK activation. Acts as an important regulator of innate immune signaling via regulation of Nodlike receptors (NLRs). Protects cells from spontaneous formation of the ripoptosome, a large multi-protein complex that has the capability to kill cancer cells in a caspase-dependent and caspase-independent manner. Suppresses ripoptosome formation by ubiquitinating RIPK1 and CASP8. Acts as a positive regulator of Wnt signaling and ubiquitinates TLE1, TLE2, TLE3, TLE4 and AES. Ubiquitination of TLE3 results in inhibition of its interaction with TCF7L2/TCF4 thereby allowing efficient recruitment and binding of the transcriptional coactivator beta-catenin to TCF7L2/TCF4 that is required to initiate a Wnt-specific transcriptional program.<ref>PMID:9230442</ref> <ref>PMID:11447297</ref> <ref>PMID:12121969</ref> <ref>PMID:14685266</ref> <ref>PMID:14645242</ref> <ref>PMID:17967870</ref> <ref>PMID:19473982</ref> <ref>PMID:21145488</ref> <ref>PMID:20154138</ref> <ref>PMID:22103349</ref> <ref>PMID:22304967</ref> <ref>PMID:17560374</ref> 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
XIAP, a member of the inhibitor of apoptosis family of proteins, is a critical regulator of apoptosis. Inhibition of the BIR domain-caspase interaction is a promising approach towards treating cancer. Previous work has been directed towards inhibiting the BIR3-caspase-9 interaction, which blocks the intrinsic apoptotic pathway; selectively inhibiting the BIR2-caspase-3 interaction would also block the extrinsic pathway. The BIR2 domain of XIAP has successfully been crystallized; peptides and small-molecule inhibitors can be soaked into these crystals, which diffract to high resolution. Here, the BIR2 apo crystal structure and the structures of five BIR2-tetrapeptide complexes are described. The structural flexibility observed on comparing these structures, along with a comparison with XIAP BIR3, affords an understanding of the structural elements that drive selectivity between BIR2 and BIR3 and which can be used to design BIR2-selective inhibitors.

The structure of XIAP BIR2: understanding the selectivity of the BIR domains.,Lukacs C, Belunis C, Crowther R, Danho W, Gao L, Goggin B, Janson CA, Li S, Remiszewski S, Schutt A, Thakur MK, Singh SK, Swaminathan S, Pandey R, Tyagi R, Gosu R, Kamath AV, Kuglstatter A Acta Crystallogr D Biol Crystallogr. 2013 Sep 1;69(Pt 9):1717-25. doi:, 10.1107/S0907444913016284. Epub 2013 Aug 15. PMID:23999295<ref>PMID:23999295</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 4j45" style="background-color:#fffaf0;"></div>

==See Also==
*[[Ubiquitin protein ligase 3D structures|Ubiquitin protein ligase 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Homo sapiens]]
[[Category: Large Structures]]
[[Category: Janson CA]]
[[Category: Lukacs CM]]