View source for 4u0i


==Crystal structure of KIT in complex with ponatinib==
<StructureSection load='4u0i' size='340' side='right'caption='[[4u0i]], [[Resolution|resolution]] 2.00&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[4u0i]] is a 1 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=4U0I OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=4U0I 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&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=0LI:3-(IMIDAZO[1,2-B]PYRIDAZIN-3-YLETHYNYL)-4-METHYL-N-{4-[(4-METHYLPIPERAZIN-1-YL)METHYL]-3-(TRIFLUOROMETHYL)PHENYL}BENZAMIDE'>0LI</scene>, <scene name='pdbligand=PO4:PHOSPHATE+ION'>PO4</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=4u0i FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4u0i OCA], [https://pdbe.org/4u0i PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=4u0i RCSB], [https://www.ebi.ac.uk/pdbsum/4u0i PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=4u0i 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 ==
Purpose: KIT is the major oncogenic driver of gastrointestinal stromal tumors (GISTs). Imatinib, sunitinib and regorafenib are approved therapies; however, efficacy is often limited by the acquisition of polyclonal secondary resistance mutations in KIT, with those located in the activation (A) loop (exons 17/18) being particularly problematic. Here we explored the KIT inhibitory activity of ponatinib in preclinical models and describe initial characterization of its activity in GIST patients. Experimental Design: The cellular and in vivo activities of ponatinib, imatinib, sunitinib and regorafenib against mutant KIT were evaluated using an accelerated mutagenesis assay and a panel of engineered and GIST-derived cell lines. The ponatinib-KIT co-structure was also determined. The clinical activity of ponatinib was examined in three GIST patients previously treated with all 3 FDA-approved agents. Results: In engineered and GIST-derived cell lines, ponatinib potently inhibited KIT exon 11 primary mutants and a range of secondary mutants, including those within the A-loop. Ponatinib also induced regression in engineered and GIST-derived tumor models containing these secondary mutations. In a mutagenesis screen, 40 nM ponatinib was sufficient to suppress outgrowth of all secondary mutants except V654A, which was suppressed at 80 nM. This inhibitory profile could be rationalized based on structural analyses. Ponatinib (30 mg daily) displayed encouraging clinical activity in two of three GIST patients. Conclusion: Ponatinib possesses potent activity against most major clinically-relevant KIT mutants, and has demonstrated preliminary evidence of activity in patients with refractory GIST. These data strongly support further evaluation of ponatinib in GIST patients.

Ponatinib inhibits polyclonal drug-resistant KIT oncoproteins and shows therapeutic potential in heavily pretreated gastrointestinal stromal tumor (GIST) patients.,Garner AP, Gozgit JM, Anjum R, Vodala S, Schrock A, Zhou T, Serrano C, Eilers G, Zhu M, Ketzer J, Wardwell S, Ning Y, Song Y, Kohlmann A, Wang F, Clackson T, Heinrich MC, Fletcher JA, Bauer S, Rivera VM Clin Cancer Res. 2014 Sep 19. pii: clincanres.1397.2014. PMID:25239608<ref>PMID:25239608</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 4u0i" 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: Dalgarno DC]]
[[Category: Zhou T]]
[[Category: Zhu X]]