Molecular dissection of the signaling and costimulatory functions of CD150 (SLAM): CD150/SAP binding and CD150-mediated costimulation.
CD150 signaling lymphocytic activation molecule (SLAM), a T/B/dendritic cell surface glycoprotein, is a costimulatory receptor involved in T-cell activation and is also a receptor for measles virus. CD150-induced signal transduction is controlled by SAP/SH2D1A, the gene that is aberrant in X-linked lymphoproliferative disease and familial hemophagocytic lymphohistiocytosis. This report shows that CD150 colocalizes with the T-cell receptor (TCR) following CD3 triggering in human peripheral blood T cells and is rapidly and reversibly tyrosine phosphorylated on TCR cross-linking. The Src-like kinases Lck and Fyn phosphorylate tyrosine residues in the cytoplasmic tail of CD150. The results demonstrate that the SAP protein has 2 modes of binding to CD150. Binding to the motif Thr-Ile-Tyr281Ala-Gln-Val occurs in a phosphotyrosine-independent fashion and to the motif Thr-Val-Tyr327Ala-Ser-Val in a phosphotyrosine-dependent manner. Within both SAP binding motifs the threonine residue at position -2 to tyrosine is essential to stabilize the interaction irrespective of tyrosine phosphorylation, a feature unique to the SAP SH2 domain. A leucine residue, Leu278, further stabilizes nonphospho binding of SAP to Tyr281 of CD150. SAP blocking of the tyrosine phosphatase SHP-2 occurs primarily on Tyr281 of CD150 because SHP-2 requires both Tyr281 and Tyr327 for binding to CD150, and SAP binds to nonphosphorylated Tyr281. CD150 exhibits lateral mobility, segregating into intercellular contacts. The lateral mobility and homophilic clustering of CD150 between neighboring cells is not dependent on SAP/CD150 interaction.
Howie
Duncan
D
Division of Immunology, RE-204, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Ave., Boston, MA 02215, USA. dhowie@caregroup.harvard.edu
Simarro
María
M
Sayos
Joan
J
Guirado
Maria
M
Sancho
Jaime
J
Terhorst
Cox
C
D000595:Amino Acid Sequence; D000818:Animals; D015703:Antigens, CD; D001665:Binding Sites / Q000502:physiology; D019556:COS Cells; D002352:Carrier Proteins / Q000378:metabolism / Q000502:physiology; D006023:Glycoproteins / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D007136:Immunoglobulins / Q000378:metabolism / Q000502:physiology*; D047908:Intracellular Signaling Peptides and Proteins; D019169:Jurkat Cells; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011485:Protein Binding / Q000502:physiology; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism; D011956:Receptors, Cell Surface; D015398:Signal Transduction; D000071179:Signaling Lymphocytic Activation Molecule Associated Protein; D000071177:Signaling Lymphocytic Activation Molecule Family Member 1; D013601:T-Lymphocytes / Q000502:physiology; D014162:Transfection; D018909:src Homology Domains / Q000502:physiology
D015703:Antigens, CD; D002352:Carrier Proteins; D006023:Glycoproteins; D007136:Immunoglobulins; D047908:Intracellular Signaling Peptides and Proteins; D011948:Receptors, Antigen, T-Cell; D011956:Receptors, Cell Surface; C114953:SH2D1A protein, human; C000604059:SLAMF1 protein, human; D000071179:Signaling Lymphocytic Activation Molecule Associated Protein; D000071177:Signaling Lymphocytic Activation Molecule Family Member 1; D011505:Protein-Tyrosine Kinases