3tub
From Proteopedia
Crystal structure of SYK kinase domain with 1-(5-(6,7-dimethoxyquinolin-4-yloxy)pyridin-2-yl)-3-((1R,2S)-2-phenylcyclopropyl)urea
Structural highlights
Function[KSYK_HUMAN] Non-receptor tyrosine kinase which mediates signal transduction downstream of a variety of transmembrane receptors including classical immunoreceptors like the B-cell receptor (BCR). Regulates several biological processes including innate and adaptive immunity, cell adhesion, osteoclast maturation, platelet activation and vascular development. Assembles into signaling complexes with activated receptors at the plasma membrane via interaction between its SH2 domains and the receptor tyrosine-phosphorylated ITAM domains. The association with the receptor can also be indirect and mediated by adapter proteins containing ITAM or partial hemITAM domains. The phosphorylation of the ITAM domains is generally mediated by SRC subfamily kinases upon engagement of the receptor. More rarely signal transduction via SYK could be ITAM-independent. Direct downstream effectors phosphorylated by SYK include VAV1, PLCG1, PI-3-kinase, LCP2 and BLNK. Initially identified as essential in B-cell receptor (BCR) signaling, it is necessary for the maturation of B-cells most probably at the pro-B to pre-B transition. Activated upon BCR engagement, it phosphorylates and activates BLNK an adapter linking the activated BCR to downstream signaling adapters and effectors. It also phosphorylates and activates PLCG1 and the PKC signaling pathway. It also phosphorylates BTK and regulates its activity in B-cell antigen receptor (BCR)-coupled signaling. Beside its function downstream of BCR plays also a role in T-cell receptor signaling. Plays also a crucial role in the innate immune response to fungal, bacterial and viral pathogens. It is for instance activated by the membrane lectin CLEC7A. Upon stimulation by fungal proteins, CLEC7A together with SYK activates immune cells inducing the production of ROS. Also activates the inflammasome and NF-kappa-B-mediated transcription of chemokines and cytokines in presence of pathogens. Regulates neutrophil degranulation and phagocytosis through activation of the MAPK signaling cascade. Also mediates the activation of dendritic cells by cell necrosis stimuli. Also involved in mast cells activation. Also functions downstream of receptors mediating cell adhesion. Relays for instance, integrin-mediated neutrophils and macrophages activation and P-selectin receptor/SELPG-mediated recruitment of leukocytes to inflammatory loci. Plays also a role in non-immune processes. It is for instance involved in vascular development where it may regulate blood and lymphatic vascular separation. It is also required for osteoclast development and function. Functions in the activation of platelets by collagen, mediating PLCG2 phosphorylation and activation. May be coupled to the collagen receptor by the ITAM domain-containing FCER1G. Also activated by the membrane lectin CLEC1B that is required for activation of platelets by PDPN/podoplanin. Involved in platelet adhesion being activated by ITGB3 engaged by fibrinogen.[1] [2] [3] [4] [5] [6] Publication Abstract from PubMedSpleen Tyrosine Kinase (Syk) is a non-receptor tyrosine kinase, over-activation of which is thought to contribute to autoimmune diseases as well as allergy and asthma. Protein kinases have a highly conserved ATP binding site, thus making challenging the design of selective small molecule inhibitors. It has been well documented that some protein kinases can be stabilized in their inactive conformations (Type-II inhibitors). Herein we describe a protein structure / ligand based approach to successfully identify ligands that bind to novel conformations of Syk. By utilizing kinase protein crystal structures both in the public domain (RCSB) and within Pfizer's protein crystal database we report the discovery of the first Syk Type-II ligands. Compounds 1 and 3 were found to bind to the DFG-out conformation of Syk while compound 2 binds to a DFG-in, C-Helix out conformation. In this instance the C-helix moved significantly to create a large hydrophobic pocket rarely seen in kinase protein crystal structures. (c) 2012 Pfizer Inc. Identification of Type-II Inhibitors Using Kinase Structures.,Lovering F, McDonald J, Whitlock GA, Glossop PA, Phillips C, Bent A, Sabnis Y, Ryan M, Fitz L, Lee J, Chang JS, Han S, Kurumbail R, Thorarensen A Chem Biol Drug Des. 2012 Jul 3. doi: 10.1111/j.1747-0285.2012.01443.x. PMID:22759374[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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