View source for 4k94


==Crystal structure of KIT D4D5 fragment in complex with anti-Kit antibody Fab19==
<StructureSection load='4k94' size='340' side='right'caption='[[4k94]], [[Resolution|resolution]] 2.40&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[4k94]] 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=4K94 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=4K94 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]] 2.4&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=NAG:N-ACETYL-D-GLUCOSAMINE'>NAG</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=4k94 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4k94 OCA], [https://pdbe.org/4k94 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=4k94 RCSB], [https://www.ebi.ac.uk/pdbsum/4k94 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=4k94 ProSAT]</span></td></tr>
</table>
== Disease ==
[https://www.uniprot.org/uniprot/KIT_HUMAN KIT_HUMAN] Defects in KIT are a cause of piebald trait (PBT) [MIM:[https://omim.org/entry/172800 172800]; also known as piebaldism. PBT is an autosomal dominant genetic developmental abnormality of pigmentation characterized by congenital patches of white skin and hair that lack melanocytes.<ref>PMID:1376329</ref> <ref>PMID:1370874</ref> <ref>PMID:1717985</ref> <ref>PMID:7687267</ref> <ref>PMID:8680409</ref> <ref>PMID:9029028</ref> <ref>PMID:9450866</ref> <ref>PMID:9699740</ref> <ref>PMID:11074500</ref>   Defects in KIT are a cause of gastrointestinal stromal tumor (GIST) [MIM:[https://omim.org/entry/606764 606764].<ref>PMID:9029028</ref> <ref>PMID:9697690</ref> <ref>PMID:9438854</ref> <ref>PMID:11505412</ref> <ref>PMID:15824741</ref>   Defects in KIT have been associated with testicular germ cell tumor (TGCT) [MIM:[https://omim.org/entry/273300 273300]. A common solid malignancy in males. Germ cell tumors of the testis constitute 95% of all testicular neoplasms.<ref>PMID:9029028</ref>   Defects in KIT are a cause of acute myelogenous leukemia (AML) [MIM:[https://omim.org/entry/601626 601626]. AML is a malignant disease in which hematopoietic precursors are arrested in an early stage of development. Note=Somatic mutations that lead to constitutive activation of KIT are detected in AML patients. These mutations fall into two classes, the most common being in-frame internal tandem duplications of variable length in the juxtamembrane region that disrupt the normal regulation of the kinase activity. Likewise, point mutations in the kinase domain can result in a constitutively activated kinase.<ref>PMID:9029028</ref> 
== Function ==
[https://www.uniprot.org/uniprot/KIT_HUMAN KIT_HUMAN] Tyrosine-protein kinase that acts as cell-surface receptor for the cytokine KITLG/SCF and plays an essential role in the regulation of cell survival and proliferation, hematopoiesis, stem cell maintenance, gametogenesis, mast cell development, migration and function, and in melanogenesis. In response to KITLG/SCF binding, KIT can activate several signaling pathways. Phosphorylates PIK3R1, PLCG1, SH2B2/APS and CBL. Activates the AKT1 signaling pathway by phosphorylation of PIK3R1, the regulatory subunit of phosphatidylinositol 3-kinase. Activated KIT also transmits signals via GRB2 and activation of RAS, RAF1 and the MAP kinases MAPK1/ERK2 and/or MAPK3/ERK1. Promotes activation of STAT family members STAT1, STAT3, STAT5A and STAT5B. Activation of PLCG1 leads to the production of the cellular signaling molecules diacylglycerol and inositol 1,4,5-trisphosphate. KIT signaling is modulated by protein phosphatases, and by rapid internalization and degradation of the receptor. Activated KIT promotes phosphorylation of the protein phosphatases PTPN6/SHP-1 and PTPRU, and of the transcription factors STAT1, STAT3, STAT5A and STAT5B. Promotes phosphorylation of PIK3R1, CBL, CRK (isoform Crk-II), LYN, MAPK1/ERK2 and/or MAPK3/ERK1, PLCG1, SRC and SHC1.<ref>PMID:7520444</ref> <ref>PMID:9528781</ref> <ref>PMID:10397721</ref> <ref>PMID:12444928</ref> <ref>PMID:12878163</ref> <ref>PMID:12511554</ref> <ref>PMID:17904548</ref> <ref>PMID:19265199</ref> <ref>PMID:21640708</ref> <ref>PMID:21135090</ref> 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Somatic oncogenic mutations in the receptor tyrosine kinase KIT function as major drivers of gastrointestinal stromal tumors and a subset of acute myeloid leukemia, melanoma, and other cancers. Although treatment of these cancers with tyrosine kinase inhibitors shows dramatic responses and durable disease control, drug resistance followed by clinical progression of disease eventually occurs in virtually all patients. In this report, we describe inhibitory KIT antibodies that bind to the membrane-proximal Ig-like D4 of KIT with significant overlap with an epitope in D4 that mediates homotypic interactions essential for KIT activation. Crystal structures of the anti-KIT antibody in complex with KIT D4 and D5 allowed design of affinity-matured libraries that were used to isolate variants with increased affinity and efficacy. Isolated antibodies showed KIT inhibition together with suppression of cell proliferation driven by ligand-stimulated WT or constitutively activated oncogenic KIT mutant. These antibodies represent a unique therapeutic approach and a step toward the development of "naked" or toxin-conjugated KIT antibodies for the treatment of KIT-driven cancers.

Structural basis for KIT receptor tyrosine kinase inhibition by antibodies targeting the D4 membrane-proximal region.,Reshetnyak AV, Nelson B, Shi X, Boggon TJ, Pavlenco A, Mandel-Bausch EM, Tome F, Suzuki Y, Sidhu SS, Lax I, Schlessinger J Proc Natl Acad Sci U S A. 2013 Oct 29;110(44):17832-7. doi:, 10.1073/pnas.1317118110. Epub 2013 Oct 14. PMID:24127596<ref>PMID:24127596</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 4k94" style="background-color:#fffaf0;"></div>

==See Also==
*[[Tyrosine kinase 3D structures|Tyrosine kinase 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Homo sapiens]]
[[Category: Large Structures]]
[[Category: Boggon TJ]]
[[Category: Lax I]]
[[Category: Resheynyak AV]]
[[Category: Schlessinger J]]