title: Identification of phosphatidylserine as a ligand for the CD300a immunoreceptor.
abstract: CD300a is a member of CD300 family molecules consisting of seven genes on human chromosome 17 and nine genes in mouse chromosome 11. CD300a has a long cytoplasmic region containing the consensus immunoreceptor tyrosine-based inhibitory motif (ITIM) sequence. Upon crosslinking with antibodies against CD300a, CD300a mediates an inhibitory signal in myeloid cells. However, the ligand for CD300a has not been identified and the physiological role of CD300a remained unclear. Here, we demonstrate that the chimeric fusion protein of CD300a extracellular domain with the Fc portion of human IgG specifically bound phosphatidylserine (PS), which is exposed on the outer leaflet of the plasma membrane of apoptotic cells. PS binding to CD300a induced SHP-1 recruitment by CD300a in mast cells in response to LPS. These results indicated that CD300a is a new PS receptor.
authors.affiliation: Department of Immunology, Division of Biomedical Sciences, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan.
authors.forename: Chigusa
authors.initials: C
authors.lastname: Nakahashi-Oda
authors.forename: Satoko
authors.initials: S
authors.lastname: Tahara-Hanaoka
authors.forename: Shin-ichiro
authors.initials: S
authors.lastname: Honda
authors.forename: Kazuko
authors.initials: K
authors.lastname: Shibuya
authors.forename: Akira
authors.initials: A
authors.lastname: Shibuya
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D002462:Cell Membrane / Q000276:immunology; D006801:Humans; D007141:Immunoglobulin Fc Fragments / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D007074:Immunoglobulin G / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D019169:Jurkat Cells; D008024:Ligands; D008407:Mast Cells / Q000276:immunology; D051379:Mice; D010718:Phosphatidylserines / Q000276:immunology*; D017434:Protein Structure, Tertiary; D011971:Receptors, Immunologic / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology
chemical_list: D015703:Antigens, CD; C515070:CD300A protein, human; D007141:Immunoglobulin Fc Fragments; D007074:Immunoglobulin G; C476771:LMIR1 protein, mouse; D008024:Ligands; D010718:Phosphatidylserines; D011971:Receptors, Immunologic; D011993:Recombinant Fusion Proteins