CD229 (Ly9) Lymphocyte Cell Surface Receptor Interacts Homophilically through Its N-Terminal Domain and Relocalizes to the Immunological Synapse

Abstract

CD229 is a member of the CD150 family of the Ig superfamily expressed on T and B cells. Receptors of this family regulate cytokine production and cytotoxicity of lymphocytes and NK cells. The cytoplasmic tail of CD229 binds to SAP, a protein that is defective in X-linked lymphoproliferative syndrome. To identify the CD229 ligand, we generated a soluble Ig fusion protein containing the two N-terminal extracellular domains of human CD229 (CD229-Ig). CD229-Ig bound to CD229-transfected cells, whereas no binding was detected on cells expressing other CD150 family receptors, showing that CD229 binds homophilically. Both human and mouse CD229 interacted with itself. Domain deletion mutants showed that the N-terminal Ig-domain mediates homophilic adhesion. CD229-CD229 binding was severely compromised when the charged amino acids E27 and E29 on the predicted B-C loop and R89 on the F-G loop of the N-terminal domain were mutated to alanine. In contrast, one mutation, R44A, enhanced the homophilic interaction. Confocal microscopy image analysis revealed relocalization of CD229 to the contact area of T and B cells during Ag-dependent immune synapse formation. Thus, CD229 is its own ligand and participates in the immunological synapse.

Differential expression of CD150 (SLAM) family receptors by human hematopoietic stem and progenitor cells

“…The following biotinylated anti-human mAbs were produced in our laboratory: CD84 (CD84.1.21), CD150 (SLAM.4), CD229 (HLy9.1.84) and CD244 (2B4.69) [9][10][11][12]. Biotinylated anti-human CD48 (99A) was provided by R. Vilella (Hospital Clinic, Barcelona, Spain) and CD150 mAbs (clones A12, 1B12, 10F5, 11G2, and 5G4) by Cox Terhorst (Harvard Medical School, Cambridge, MA, USA).…”

Engagement of SLAMF3 enhances CD4 + T-cell sensitivity to IL-2 and favors regulatory T-cell polarization in systemic lupus erythematosus

“…This article is a PNAS Direct Submission. 1 To whom correspondence should be addressed. Email: dcomte@bidmc.harvard.edu.…”

“…ignaling lymphocytic activation molecule family members (SLAMF1-9) are type I transmembrane glycoprotein cell surface receptors that deliver downstream signals on their engagement (1). SLAMF3 (CD229/Ly9) is expressed on T cells, B cells, NK cells, macrophages, and dendritic cells (2).…”

Large-scale screening for novel low-affinity extracellular protein interactions

“…These cDNAs were cloned from either existing MGC clones or amplified from mixed-tissue human cDNA essentially as described (Collins et al 2004). Within this set of proteins are published negative interactions (Martin et al 2001;Kumaresan et al 2002;Falco et al 2004;Flaig et al 2004;Romero et al 2005), outlined with black circles in Figure 1D.…”