8dfm

Ectodomain of full-length wild-type KIT-SCF dimers

spinqualitylabelsall models 8dfm, resolution 3.45Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 8dfm is a 4 chain structure with sequence from Homo sapiens. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: Electron Microscopy, Resolution 3.45Å Ligands: NAG Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Disease KIT_HUMAN Defects in KIT are a cause of piebald trait (PBT) [MIM: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. Defects in KIT are a cause of gastrointestinal stromal tumor (GIST) [MIM:606764. Defects in KIT have been associated with testicular germ cell tumor (TGCT) [MIM:273300. A common solid malignancy in males. Germ cell tumors of the testis constitute 95% of all testicular neoplasms. Defects in KIT are a cause of acute myelogenous leukemia (AML) [MIM: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. Function 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. Publication Abstract from PubMed The receptor tyrosine kinase KIT and its ligand stem cell factor (SCF) are required for the development of hematopoietic stem cells, germ cells, and other cells. A variety of human cancers, such as acute myeloid leukemia, gastrointestinal stromal tumor, and mast cell leukemia, are driven by somatic gain-of-function KIT mutations. Here, we report cryo electron microscopy (cryo-EM) structural analyses of full-length wild-type and two oncogenic KIT mutants, which show that the overall symmetric arrangement of the extracellular domain of ligand-occupied KIT dimers contains asymmetric D5 homotypic contacts juxtaposing the plasma membrane. Mutational analysis of KIT reveals in D5 region an "Achilles heel" for therapeutic intervention. A ligand-sensitized oncogenic KIT mutant exhibits a more comprehensive and stable D5 asymmetric conformation. A constitutively active ligand-independent oncogenic KIT mutant adopts a V-shaped conformation solely held by D5-mediated contacts. Binding of SCF to this mutant fully restores the conformation of wild-type KIT dimers, including the formation of salt bridges responsible for D4 homotypic contacts and other hallmarks of SCF-induced KIT dimerization. These experiments reveal an unexpected structural plasticity of oncogenic KIT mutants and a therapeutic target in D5. Cryo-EM analyses of KIT and oncogenic mutants reveal structural oncogenic plasticity and a target for therapeutic intervention.,Krimmer SG, Bertoletti N, Suzuki Y, Katic L, Mohanty J, Shu S, Lee S, Lax I, Mi W, Schlessinger J Proc Natl Acad Sci U S A. 2023 Mar 28;120(13):e2300054120. doi: , 10.1073/pnas.2300054120. Epub 2023 Mar 21. PMID:36943885 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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