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From Proteopedia
Autoinhibited intact human ZAP-70
Structural highlights
Disease[ZAP70_HUMAN] Defects in ZAP70 are the cause of selective T-cell defect (STCD) [MIM:269840]. A form of severe combined immunodeficiency characterized by a selective absence of CD8+ T cells.[1] [2] [3] [4] [5] Function[ZAP70_HUMAN] Tyrosine kinase that plays an essential role in regulation of the adaptive immune response. Regulates motility, adhesion and cytokine expression of mature T-cells, as well as thymocyte development. Contributes also to the development and activation of primary B-lymphocytes. When antigen presenting cells (APC) activate T-cell receptor (TCR), a serie of phosphorylations lead to the recruitment of ZAP70 to the doubly phosphorylated TCR component CD247/CD3Z through ITAM motif at the plasma membrane. This recruitment serves to localization to the stimulated TCR and to relieve its autoinhibited conformation. Release of ZAP70 active conformation is further stabilized by phosphorylation mediated by LCK. Subsequently, ZAP70 phosphorylates at least 2 essential adapter proteins: LAT and LCP2. In turn, a large number of signaling molecules are recruited and ultimately lead to lymphokine production, T-cell proliferation and differentiation. Furthermore, ZAP70 controls cytoskeleton modifications, adhesion and mobility of T-lymphocytes, thus ensuring correct delivery of effectors to the APC. ZAP70 is also required for TCR-CD247/CD3Z internalization and degradation through interaction with the E3 ubiquitin-protein ligase CBL and adapter proteins SLA and SLA2. Thus, ZAP70 regulates both T-cell activation switch on and switch off by modulating TCR expression at the T-cell surface. During thymocyte development, ZAP70 promotes survival and cell-cycle progression of developing thymocytes before positive selection (when cells are still CD4/CD8 double negative). Additionally, ZAP70-dependent signaling pathway may also contribute to primary B-cells formation and activation through B-cell receptor (BCR).[6] [7] [8] [9] [10] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedZAP-70, a cytoplasmic tyrosine kinase required for T cell antigen receptor signaling, is controlled by a regulatory segment that includes a tandem SH2 unit responsible for binding to immunoreceptor tyrosine-based activation motifs (ITAMs). The crystal structure of autoinhibited ZAP-70 reveals that the inactive kinase domain adopts a conformation similar to that of cyclin-dependent kinases and Src kinases. The autoinhibitory mechanism of ZAP-70 is, however, distinct and involves interactions between the regulatory segment and the hinge region of the kinase domain that reduce its flexibility. Two tyrosine residues in the SH2-kinase linker that activate ZAP-70 when phosphorylated are involved in aromatic-aromatic interactions that connect the linker to the kinase domain. These interactions are inconsistent with ITAM binding, suggesting that destabilization of this autoinhibited ZAP-70 conformation is the first step in kinase activation. Structural basis for the inhibition of tyrosine kinase activity of ZAP-70.,Deindl S, Kadlecek TA, Brdicka T, Cao X, Weiss A, Kuriyan J Cell. 2007 May 18;129(4):735-46. PMID:17512407[11] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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