title: Identification of Grb2 as a novel binding partner of the signaling lymphocytic activation molecule-associated protein binding receptor CD229.
abstract: Ag recognition by the TCR determines the subsequent fate of the T cell and is regulated by the involvement of other cell surface molecules, termed coreceptors. CD229 is a lymphocyte cell surface molecule that belongs to the CD150 family of receptors. Upon tyrosine phosphorylation, CD229 recruits various signaling molecules to the membrane. One of these molecules is the signaling lymphocytic activation molecule-associated protein, of which a deficiency leads to the X-linked lymphoproliferative syndrome. We report that CD229 interacts in a phosphorylation-dependent manner with Grb2. We mapped this interaction showing that the Src homology 2 domain of Grb2 and the tyrosine residue Y606 in CD229 are required for CD229-Grb2 complex formation. The Grb2 motif in the cytoplasmic tail of CD229 is distinct and independent from the two tyrosines required for efficient signaling lymphocytic activation molecule-associated protein recruitment. CD229, but not other members of the CD150 family, directly bound Grb2. We also demonstrate that CD229 precipitates with Grb2 in T lymphocytes after pervanadate treatment, as well as CD229 or TCR ligation. Interestingly, the CD229 mutant lacking the Grb2 binding site is not internalized after CD229 engagement with specific Abs. Moreover, a dominant negative form of Grb2 (containing only Src homology 2 domain) impaired CD229 endocytosis. Unexpectedly, Erk phosphorylation was partially inhibited after activation of CD229 plus CD3. Consistent with this, CD229 ligation partially inhibited TCR signaling in peripheral blood cells and CD229-Jurkat cells transfected with the 3XNFAT-luciferase reporter construct. Altogether, the data suggest a model whereby CD229 ligation attenuates TCR signaling and Grb2 recruitment to CD229 controls its rate of internalization.
authors.affiliation: Unitat d'Immunología, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Departament de Biologia Cellular i Anatomia Patològica, Facultat de Medicina, Universitat de Barcelona, Barcelona, Spain. martin_andorra@ub.edu
authors.forename: Margarita
authors.initials: M
authors.lastname: Martín
authors.forename: Juana M
authors.initials: JM
authors.lastname: Del Valle
authors.forename: Ifigènia
authors.initials: I
authors.lastname: Saborit
authors.forename: Pablo
authors.initials: P
authors.lastname: Engel
mesh_terms: D033962:Adaptor Protein Complex 2 / Q000378:metabolism; D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism* / Q000502:physiology; D019943:Amino Acid Substitution / Q000235:genetics / Q000276:immunology; D015703:Antigens, CD / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D001665:Binding Sites / Q000276:immunology; D016207:Cytokines / Q000037:antagonists & inhibitors / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D004705:Endocytosis / Q000276:immunology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D051380:GRB2 Adaptor Protein; D006023:Glycoproteins / Q000378:metabolism*; D006801:Humans; D007136:Immunoglobulins / Q000378:metabolism*; D019169:Jurkat Cells; D008024:Ligands; D008213:Lymphocyte Activation / Q000276:immunology*; D010446:Peptide Fragments / Q000378:metabolism / Q000502:physiology; D010766:Phosphorylation; D011485:Protein Binding / Q000276:immunology; D021381:Protein Transport / Q000276:immunology; D011948:Receptors, Antigen, T-Cell / Q000037:antagonists & inhibitors / Q000276:immunology / Q000378:metabolism; D011956:Receptors, Cell Surface; D015398:Signal Transduction / Q000276:immunology*; D000071176:Signaling Lymphocytic Activation Molecule Family; D000071177:Signaling Lymphocytic Activation Molecule Family Member 1; D020798:Two-Hybrid System Techniques; D014443:Tyrosine / Q000235:genetics; D018909:src Homology Domains / Q000502:physiology
chemical_list: D033962:Adaptor Protein Complex 2; D048868:Adaptor Proteins, Signal Transducing; D015703:Antigens, CD; D016207:Cytokines; D051380:GRB2 Adaptor Protein; C495948:GRB2 protein, human; D006023:Glycoproteins; D007136:Immunoglobulins; C430423:LY9 protein, human; D008024:Ligands; D010446:Peptide Fragments; D011948:Receptors, Antigen, T-Cell; D011956:Receptors, Cell Surface; C000604059:SLAMF1 protein, human; D000071176:Signaling Lymphocytic Activation Molecule Family; D000071177:Signaling Lymphocytic Activation Molecule Family Member 1; D014443:Tyrosine; D048049:Extracellular Signal-Regulated MAP Kinases