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From Proteopedia
CRYSTAL STRUCTURE OF THE XLP PROTEIN SAP IN COMPLEX WITH SLAM PHOSPHOPEPTIDE
Structural highlights
Disease[SH21A_HUMAN] Defects in SH2D1A are a cause of lymphoproliferative syndrome X-linked type 1 (XLP1) [MIM:308240]; also known as X-linked lymphoproliferative disease (XLPD) or Duncan disease. XLP is a rare immunodeficiency characterized by extreme susceptibility to infection with Epstein-Barr virus (EBV). Symptoms include severe or fatal mononucleosis, acquired hypogammaglobulinemia, pancytopenia and malignant lymphoma.[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] Function[SH21A_HUMAN] Inhibitor of the SLAM self-association. Acts by blocking recruitment of the SH2-domain-containing signal-transduction molecule SHP-2 to a docking site in the SLAM cytoplasmic region. Mediates interaction between FYN and SLAMF1. May also regulate the activity of the neurotrophin receptors NTRK1, NTRK2 and NTRK3. [SLAF1_HUMAN] High-affinity self-ligand important in bidirectional T-cell to B-cell stimulation. SLAM-induced signal-transduction events in T-lymphocytes are different from those in B-cells. Two modes of SLAM signaling are likely to exist: one in which the inhibitor SH2D1A acts as a negative regulator and another in which protein-tyrosine phosphatase 2C (PTPN11)-dependent signal transduction operates. 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 PubMedSAP, the product of the gene mutated in X-linked lymphoproliferative syndrome (XLP), consists of a single SH2 domain that has been shown to bind the cytoplasmic tail of the lymphocyte coreceptor SLAM. Here we describe structures that show that SAP binds phosphorylated and nonphosphorylated SLAM peptides in a similar mode, with the tyrosine or phosphotyrosine residue inserted into the phosphotyrosine-binding pocket. We find that specific interactions with residues N-terminal to the tyrosine, in addition to more characteristic C-terminal interactions, stabilize the complexes. A phosphopeptide library screen and analysis of mutations identified in XLP patients confirm that these extended interactions are required for SAP function. Further, we show that SAP and the similar protein EAT-2 recognize the sequence motif TIpYXX(V/I). Crystal structures of the XLP protein SAP reveal a class of SH2 domains with extended, phosphotyrosine-independent sequence recognition.,Poy F, Yaffe MB, Sayos J, Saxena K, Morra M, Sumegi J, Cantley LC, Terhorst C, Eck MJ Mol Cell. 1999 Oct;4(4):555-61. PMID:10549287[11] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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