View source for 4w4z


==Structure of the EphA4 LBD in complex with peptide==
<StructureSection load='4w4z' size='340' side='right'caption='[[4w4z]], [[Resolution|resolution]] 2.41&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[4w4z]] is a 8 chain structure with sequence from [https://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens] and [https://en.wikipedia.org/wiki/Synthetic_construct Synthetic construct]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4W4Z OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=4W4Z 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]] 2.41&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=BAL:BETA-ALANINE'>BAL</scene>, <scene name='pdbligand=GOL:GLYCEROL'>GOL</scene>, <scene name='pdbligand=HEZ:HEXANE-1,6-DIOL'>HEZ</scene>, <scene name='pdbligand=NH2:AMINO+GROUP'>NH2</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=4w4z FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4w4z OCA], [https://pdbe.org/4w4z PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=4w4z RCSB], [https://www.ebi.ac.uk/pdbsum/4w4z PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=4w4z ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/EPHA4_HUMAN EPHA4_HUMAN] Receptor tyrosine kinase which binds membrane-bound ephrin family ligands residing on adjacent cells, leading to contact-dependent bidirectional signaling into neighboring cells. The signaling pathway downstream of the receptor is referred to as forward signaling while the signaling pathway downstream of the ephrin ligand is referred to as reverse signaling. Highly promiscuous, it has the unique property among Eph receptors to bind and to be physiologically activated by both GPI-anchored ephrin-A and transmembrane ephrin-B ligands including EFNA1 and EFNB3. Upon activation by ephrin ligands, modulates cell morphology and integrin-dependent cell adhesion through regulation of the Rac, Rap and Rho GTPases activity. Plays an important role in the development of the nervous system controlling different steps of axonal guidance including the establishment of the corticospinal projections. May also control the segregation of motor and sensory axons during neuromuscular circuit development. Beside its role in axonal guidance plays a role in synaptic plasticity. Activated by EFNA1 phosphorylates CDK5 at 'Tyr-15' which in turn phosphorylates NGEF regulating RHOA and dendritic spine morphogenesis. In the nervous system, plays also a role in repair after injury preventing axonal regeneration and in angiogenesis playing a role in central nervous system vascular formation. Additionally, its promiscuity makes it available to participate in a variety of cell-cell signaling regulating for instance the development of the thymic epithelium.<ref>PMID:17143272</ref> 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
The EphA4 receptor is highly expressed in the nervous system and recent findings suggest that its signaling activity hinders neural repair and exacerbates certain neurodegenerative processes. EphA4 has also been implicated in cancer progression. Thus, EphA4 inhibitors represent potential therapeutic leads and useful research tools to elucidate the role of EphA4 in physiology and disease. Here we report the structure of a cyclic peptide antagonist, APY, in complex with the EphA4 ligand-binding domain (LBD), which represents the first structure of a cyclic peptide bound to a receptor tyrosine kinase. The structure shows that the dodecameric APY efficiently occupies the ephrin ligand-binding pocket of EphA4 and promotes a "closed" conformation of the surrounding loops. Structure-guided relaxation of the strained APY beta-turn and amidation of the C terminus to allow an additional intrapeptide hydrogen bond yielded APY-betaAla8.am, an improved APY derivative that binds to EphA4 with nanomolar affinity. APY-betaAla8.am potently inhibits ephrin-induced EphA4 activation in cells and EphA4-dependent neuronal growth cone collapse, while retaining high selectivity for EphA4. The two crystal structures of APY and APY-betaAla8.am bound to EphA4, in conjunction with secondary phage display screens, highlighted peptide residues that are essential for EphA4 binding as well as residues that can be modified. Thus, the APY scaffold represents an exciting prototype, particularly since cyclic peptides have potentially favorable metabolic stability and are emerging as an important class of molecules for disruption of protein-protein interactions.

Development and Structural Analysis of a Nanomolar Cyclic Peptide Antagonist for the EphA4 Receptor.,Lamberto I, Lechtenberg BC, Olson E, Mace PD, Dawson PE, Riedl SJ, Pasquale EB ACS Chem Biol. 2014 Sep 30. PMID:25268696<ref>PMID:25268696</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 4w4z" style="background-color:#fffaf0;"></div>

==See Also==
*[[Ephrin receptor 3D structures|Ephrin receptor 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Homo sapiens]]
[[Category: Large Structures]]
[[Category: Synthetic construct]]
[[Category: Lechtenberg BC]]
[[Category: Mace PD]]
[[Category: Riedl SJ]]