title: A family of highly diverse human and mouse genes structurally links leukocyte FcR, gp42 and PECAM-1.
abstract: A group of genes encoding proteins structurally related to the leukocyte Fc receptors (FcRs) and termed the IFGP family was identified in human and mouse. Sequences of four human and two mouse cDNAs predict proteins differing by domain composition. One of the mouse cDNAs encodes a secreted protein, which, in addition to four immunoglobulin (Ig)-like domains, contains a scavenger receptor superfamily-related domain at the C-terminus. The other cDNAs code for the type I transmembrane proteins with the extracellular parts comprised of one to six Ig-like domains. Five homologous types of the Ig-like domains were defined and each protein was found to have a unique combination of the domain types. The cytoplasmic tails of the transmembrane proteins show different patterns of the tyrosine-based signal motifs. While the human IFGP members appear to be B-cell antigens, the mouse genes have a broader tissue distribution with predominant expression in brain. Sequence comparisons revealed that the IFGP family may be regarded as a phylogenetic link joining the leukocyte FcRs with the rat NK cell-specific gp42 antigen and platelet endothelial cell adhesion molecule-1 (PECAM-1), two mammalian leukocyte receptors whose close relatives were not found previously. It is suggested that FcRs, the IFGP proteins and gp42 have arisen by a series of duplications from a common ancestor receptor comprised of five Ig-like domains. The organization of the human genes shows that the IFGP family evolved through differential gain and loss of exons due to recombination and/or mutation accumulation in the duplicated copies.
authors.affiliation: Laboratory of Immunogenetics, Institute of Cytology and Genetics, Lavrentjev st. 10, Novosibirsk 630090, Russia.
authors.forename: Sergei V
authors.initials: SV
authors.lastname: Guselnikov
authors.forename: Svetlana A
authors.initials: SA
authors.lastname: Ershova
authors.forename: Ludmila V
authors.initials: LV
authors.lastname: Mechetina
authors.forename: Alexander M
authors.initials: AM
authors.lastname: Najakshin
authors.forename: Olga Y
authors.initials: OY
authors.lastname: Volkova
authors.forename: Boris Y
authors.initials: BY
authors.lastname: Alabyev
authors.forename: Alexander V
authors.initials: AV
authors.lastname: Taranin
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D015703:Antigens, CD; D000951:Antigens, Neoplasm; D000954:Antigens, Surface; D030161:Avian Proteins; D001402:B-Lymphocytes / Q000378:metabolism; D051926:Basigin; D001798:Blood Proteins; D005796:Genes; D006801:Humans; D007136:Immunoglobulins / Q000737:chemistry; D007962:Leukocytes / Q000276:immunology; D008562:Membrane Glycoproteins / Q000235:genetics*; D051379:Mice; D008969:Molecular Sequence Data; D010802:Phylogeny; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000235:genetics*; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000096:biosynthesis; D011961:Receptors, Fc / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics*; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D014018:Tissue Distribution
chemical_list: D015703:Antigens, CD; D000951:Antigens, Neoplasm; D000954:Antigens, Surface; D030161:Avian Proteins; C497886:BSG protein, human; D001798:Blood Proteins; C102624:Bsg protein, Gallus gallus; C497887:Bsg protein, mouse; C079432:Bsg protein, rat; D007136:Immunoglobulins; D008562:Membrane Glycoproteins; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D012333:RNA, Messenger; D011961:Receptors, Fc; D051926:Basigin