3pjc
From Proteopedia
Crystal structure of JAK3 complexed with a potent ATP site inhibitor showing high selectivity within the Janus kinase family
Structural highlights
Disease[JAK3_HUMAN] Defects in JAK3 are a cause of severe combined immunodeficiency autosomal recessive T-cell-negative/B-cell-positive/NK-cell-negative (T(-)B(+)NK(-) SCID) [MIM:600802]. A form of severe combined immunodeficiency (SCID), a genetically and clinically heterogeneous group of rare congenital disorders characterized by impairment of both humoral and cell-mediated immunity, leukopenia, and low or absent antibody levels. Patients present in infancy recurrent, persistent infections by opportunistic organisms. The common characteristic of all types of SCID is absence of T-cell-mediated cellular immunity due to a defect in T-cell development.[1] [2] [3] [:][4] [5] [6] [7] [8] Function[JAK3_HUMAN] Non-receptor tyrosine kinase involved in various processes such as cell growth, development, or differentiation. Mediates essential signaling events in both innate and adaptive immunity and plays a crucial role in hematopoiesis during T-cells development. In the cytoplasm, plays a pivotal role in signal transduction via its association with type I receptors sharing the common subunit gamma such as IL2R, IL4R, IL7R, IL9R, IL15R and IL21R. Following ligand binding to cell surface receptors, phosphorylates specific tyrosine residues on the cytoplasmic tails of the receptor, creating docking sites for STATs proteins. Subsequently, phosphorylates the STATs proteins once they are recruited to the receptor. Phosphorylated STATs then form homodimer or heterodimers and translocate to the nucleus to activate gene transcription. For example, upon IL2R activation by IL2, JAK1 and JAK3 molecules bind to IL2R beta (IL2RB) and gamma chain (IL2RG) subunits inducing the tyrosine phosphorylation of both receptor subunits on their cytoplasmic domain. Then, STAT5A AND STAT5B are recruited, phosphorylated and activated by JAK1 and JAK3. Once activated, dimerized STAT5 translocates to the nucleus and promotes the transcription of specific target genes in a cytokine-specific fashion.[9] [10] [11] Publication Abstract from PubMedWe describe a synthetic approach toward the rapid modification of phenyl-indolyl maleimides and the discovery of potent Jak3 inhibitor 1 with high selectivity within the Jak kinase family. We provide a rationale for this unprecedented selectivity based on the X-ray crystal structure of an analogue of 1 bound to the ATP-binding site of Jak3. While equally potent compared to the Pfizer pan Jak inhibitor CP-690,550 (2) in an enzymatic Jak3 assay, compound 1 was found to be 20-fold less potent in cellular assays measuring cytokine-triggered signaling through cytokine receptors containing the common gamma chain (gammaC). Contrary to compound 1, compound 2 inhibited Jak1 in addition to Jak3. Permeability and cellular concentrations of compounds 1 and 2 were similar. As Jak3 always cooperates with Jak1 for signaling, we speculate that specific inhibition of Jak3 is not sufficient to efficiently block gammaC cytokine signal transduction required for strong immunosuppression. Identification of a Potent Janus Kinase 3 Inhibitor with High Selectivity within the Janus Kinase Family.,Thoma G, Nuninger F, Falchetto R, Hermes E, Tavares GA, Vangrevelinghe E, Zerwes HG J Med Chem. 2010 Dec 14. PMID:21155605[12] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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