9t23

Crystal Structure of 5 bound to the PH domain of Btk

spinqualitylabelsall models 9t23, resolution 1.84Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 9t23 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: X-ray diffraction, Resolution 1.845Å Ligands: A1JS6, MG, ZN Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Disease BTK_HUMAN Defects in BTK are the cause of X-linked agammaglobulinemia (XLA) [MIM:300755; also known as X-linked agammaglobulinemia type 1 (AGMX1) or immunodeficiency type 1 (IMD1). XLA is a humoral immunodeficiency disease which results in developmental defects in the maturation pathway of B-cells. Affected boys have normal levels of pre-B-cells in their bone marrow but virtually no circulating mature B-lymphocytes. This results in a lack of immunoglobulins of all classes and leads to recurrent bacterial infections like otitis, conjunctivitis, dermatitis, sinusitis in the first few years of life, or even some patients present overwhelming sepsis or meningitis, resulting in death in a few hours. Treatment in most cases is by infusion of intravenous immunoglobulin. Defects in BTK may be the cause of X-linked hypogammaglobulinemia and isolated growth hormone deficiency (XLA-IGHD) [MIM:307200; also known as agammaglobulinemia and isolated growth hormone deficiency or Fleisher syndrome or isolated growth hormone deficiency type 3 (IGHD3). In rare cases XLA is inherited together with isolated growth hormone deficiency (IGHD). Function BTK_HUMAN Non-receptor tyrosine kinase indispensable for B lymphocyte development, differentiation and signaling. Binding of antigen to the B-cell antigen receptor (BCR) triggers signaling that ultimately leads to B-cell activation. After BCR engagement and activation at the plasma membrane, phosphorylates PLCG2 at several sites, igniting the downstream signaling pathway through calcium mobilization, followed by activation of the protein kinase C (PKC) family members. PLCG2 phosphorylation is performed in close cooperation with the adapter protein B-cell linker protein BLNK. BTK acts as a platform to bring together a diverse array of signaling proteins and is implicated in cytokine receptor signaling pathways. Plays an important role in the function of immune cells of innate as well as adaptive immunity, as a component of the Toll-like receptors (TLR) pathway. The TLR pathway acts as a primary surveillance system for the detection of pathogens and are crucial to the activation of host defense. Especially, is a critical molecule in regulating TLR9 activation in splenic B-cells. Within the TLR pathway, induces tyrosine phosphorylation of TIRAP which leads to TIRAP degradation. BTK plays also a critical role in transcription regulation. Induces the activity of NF-kappa-B, which is involved in regulating the expression of hundreds of genes. BTK is involved on the signaling pathway linking TLR8 and TLR9 to NF-kappa-B. Transiently phosphorylates transcription factor GTF2I on tyrosine residues in response to BCR. GTF2I then translocates to the nucleus to bind regulatory enhancer elements to modulate gene expression. ARID3A and NFAT are other transcriptional target of BTK. BTK is required for the formation of functional ARID3A DNA-binding complexes. There is however no evidence that BTK itself binds directly to DNA. BTK has a dual role in the regulation of apoptosis. Publication Abstract from PubMed Bruton's Tyrosine Kinase (BTK) is a validated target for hematological malignancies, with numerous FDA-approved inhibitors on the market. Current therapies target the highly conserved ATP binding site and hence limit the therapeutic index given the site's highly conserved nature across the kinome. We explore a novel approach for BTK inhibition by targeting the PH domain-mediated membrane recruitment and activation of BTK. We have identified a fragment which covalently modifies a lysine in the inositol phosphate (PIP3) binding site and inhibits the binding of a soluble PIP3 headgroup analog to the PH domain. Fragment growth and an extensive structure-binding relationship study uncovered 27 crystal structures and a best-in-class analog, 24. Evaluation of pK(a) values of the targeted lysine in BTK and other PH domains suggests this as a more general approach to PH domain inhibition. Targeting a Pleckstrin Homology Domain with a Lysine-Reactive Covalent Binder.,West RM, Bizga Nicolescu RC, Brear P, Wagstaff J, Blaszczyk BK, Deingruber T, Sanders MG, Perez-Areales FJ, Spring DR, Hyvonen M J Med Chem. 2026 May 14. doi: 10.1021/acs.jmedchem.5c03818. PMID:42130460 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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