2yz1 | pdb_00002yz1
Crystal structure of the ligand-binding domain of murine SHPS-1/SIRP alpha
Structural highlights
Function[SHPS1_MOUSE] Immunoglobulin-like cell surface receptor for CD47. Acts as docking protein and induces translocation of PTPN6, PTPN11 and other binding partners from the cytosol to the plasma membrane. Supports adhesion of cerebellar neurons, neurite outgrowth and glial cell attachment. May play a key role in intracellular signaling during synaptogenesis and in synaptic function. Involved in the negative regulation of receptor tyrosine kinase-coupled cellular responses induced by cell adhesion, growth factors or insulin. Mediates negative regulation of phagocytosis, mast cell activation and dendritic cell activation. CD47 binding prevents maturation of immature dendritic cells and inhibits cytokine production by mature dendritic cells (By similarity).[1] 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 PubMedSRC homology 2 domain-containing protein tyrosine phosphatase substrate 1 (SHPS-1 or SIRP alpha/BIT) is an immunoglobulin (Ig) superfamily transmembrane receptor and a member of the signal regulatory protein (SIRP) family involved in cell-cell interaction. SHPS-1 binds to its ligand CD47 to relay an inhibitory signal for cellular responses, whereas SIRPbeta, an activating member of the same family, does not bind to CD47 despite sharing a highly homologous ligand-binding domain with SHPS-1. To address the molecular basis for specific CD47 recognition by SHPS-1, we present the crystal structure of the ligand-binding domain of murine SHPS-1 (mSHPS-1). Folding topology revealed that mSHPS-1 adopts an I2-set Ig fold, but its overall structure resembles IgV domains of antigen receptors, although it has an extended loop structure (C'E loop), which forms a dimer interface in the crystal. Site-directed mutagenesis studies of mSHPS-1 identified critical residues for CD47 binding including sites in the C'E loop and regions corresponding to complementarity-determining regions of antigen receptors. The structural and functional features of mSHPS-1 are consistent with the human SHPS-1 structure except that human SHPS-1 has an additional beta-strand D. These results suggest that the variable complementarity-determining region-like loop structures in the binding surface of SHPS-1 are generally required for ligand recognition in a manner similar to that of antigen receptors, which may explain the diverse ligand-binding specificities of SIRP family receptors. Structural insight into the specific interaction between murine SHPS-1/SIRP alpha and its ligand CD47.,Nakaishi A, Hirose M, Yoshimura M, Oneyama C, Saito K, Kuki N, Matsuda M, Honma N, Ohnishi H, Matozaki T, Okada M, Nakagawa A J Mol Biol. 2008 Jan 18;375(3):650-60. Epub 2007 Nov 7. PMID:18045614[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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