CD150 association with either the SH2-containing inositol phosphatase or the SH2-containing protein tyrosine phosphatase is regulated by the adaptor protein SH2D1A.
CD150 (SLAM/IPO-3) is a cell surface receptor that, like the B cell receptor, CD40, and CD95, can transmit positive or negative signals. CD150 can associate with the SH2-containing inositol phosphatase (SHIP), the SH2-containing protein tyrosine phosphatase (SHP-2), and the adaptor protein SH2 domain protein 1A (SH2D1A/DSHP/SAP, also called Duncan's disease ... SH2-protein (DSHP) or SLAM-associated protein (SAP)). Mutations in SH2D1A are found in X-linked lymphoproliferative syndrome and non-Hodgkin's lymphomas. Here we report that SH2D1A is expressed in tonsillar B cells and in some B lymphoblastoid cell lines, where CD150 coprecipitates with SH2D1A and SHIP. However, in SH2D1A-negative B cell lines, including B cell lines from X-linked lymphoproliferative syndrome patients, CD150 associates only with SHP-2. SH2D1A protein levels are up-regulated by CD40 cross-linking and down-regulated by B cell receptor ligation. Using GST-fusion proteins with single replacements of tyrosine at Y269F, Y281F, Y307F, or Y327F in the CD150 cytoplasmic tail, we found that the same phosphorylated Y281 and Y327 are essential for both SHP-2 and SHIP binding. The presence of SH2D1A facilitates binding of SHIP to CD150. Apparently, SH2D1A may function as a regulator of alternative interactions of CD150 with SHP-2 or SHIP via a novel TxYxxV/I motif (immunoreceptor tyrosine-based switch motif (ITSM)). Multiple sequence alignments revealed the presence of this TxYxxV/I motif not only in CD2 subfamily members but also in the cytoplasmic domains of the members of the SHP-2 substrate 1, sialic acid-binding Ig-like lectin, carcinoembryonic Ag, and leukocyte-inhibitory receptor families.
Mesh Terms:
Amino Acid Sequence, Antigens, CD, B-Lymphocytes, Carrier Proteins, Cell Line, Transformed, Cells, Cultured, Cytoplasm, Glycoproteins, Humans, Immunoglobulins, Intracellular Signaling Peptides and Proteins, Jurkat Cells, Models, Molecular, Molecular Sequence Data, Mutagenesis, Site-Directed, Peptide Fragments, Phosphatidylinositol-3,4,5-Trisphosphate 5-Phosphatases, Phosphoric Monoester Hydrolases, Protein Binding, Protein Tyrosine Phosphatase, Non-Receptor Type 11, Protein Tyrosine Phosphatase, Non-Receptor Type 6, Protein Tyrosine Phosphatases, Receptors, Antigen, B-Cell, Receptors, Cell Surface, Recombinant Fusion Proteins, SH2 Domain-Containing Protein Tyrosine Phosphatases, Signaling Lymphocytic Activation Molecule Associated Protein, Signaling Lymphocytic Activation Molecule Family Member 1, Tumor Cells, Cultured, Tyrosine, src Homology Domains
Amino Acid Sequence, Antigens, CD, B-Lymphocytes, Carrier Proteins, Cell Line, Transformed, Cells, Cultured, Cytoplasm, Glycoproteins, Humans, Immunoglobulins, Intracellular Signaling Peptides and Proteins, Jurkat Cells, Models, Molecular, Molecular Sequence Data, Mutagenesis, Site-Directed, Peptide Fragments, Phosphatidylinositol-3,4,5-Trisphosphate 5-Phosphatases, Phosphoric Monoester Hydrolases, Protein Binding, Protein Tyrosine Phosphatase, Non-Receptor Type 11, Protein Tyrosine Phosphatase, Non-Receptor Type 6, Protein Tyrosine Phosphatases, Receptors, Antigen, B-Cell, Receptors, Cell Surface, Recombinant Fusion Proteins, SH2 Domain-Containing Protein Tyrosine Phosphatases, Signaling Lymphocytic Activation Molecule Associated Protein, Signaling Lymphocytic Activation Molecule Family Member 1, Tumor Cells, Cultured, Tyrosine, src Homology Domains
J. Immunol.
Date: May. 01, 2001
PubMed ID: 11313386
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