title: Synaptic membrane glycoproteins gp65 and gp55 are new members of the immunoglobulin superfamily.
abstract: Glycoproteins gp65 and gp55 are major components of synaptic membranes prepared from rat forebrain. Both are recognized by the monoclonal antibody SMgp65. We have used SMgp65 to screen a rat brain cDNA expression library. Two sets of overlapping cDNAs that contain open reading frames of 397 and 281 amino acids were isolated. The deduced proteins are members of the immunoglobulin (Ig) superfamily containing three and two Ig domains, respectively. The common part has approximately 40% sequence identity with neurothelin/basigin. The identity of the proteins as gp65 and gp55 was confirmed by production of new antisera against a common recombinant protein fragment. These antisera immunoprecipitate gp65 and gp55. Furthermore, expression of gp65 and gp55 cDNAs in human 293 cells treated with tunicamycin results in the production of unglycosylated core proteins of identical size to deglycosylated gp65 and gp55. Northern analysis revealed that gp65 transcripts are brain-specific, whereas gp55 is expressed in most tissues and cell lines examined. The tissue distribution was confirmed at the protein level though the pattern of glycosylation of gp55 varies between tissues. In situ hybridization experiments with a common and a gp65-specific probe suggest differential expression of gp65 and gp55 transcripts in the rat brain.
authors.affiliation: Department of Neurochemistry and Molecular Biology, Federal Institute for Neurobiology, Magdeburg, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Langnaese
authors.forename: P W
authors.initials: PW
authors.lastname: Beesley
authors.forename: E D
authors.initials: ED
authors.lastname: Gundelfinger
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D003001:Cloning, Molecular; D006801:Humans; D007136:Immunoglobulins / Q000737:chemistry*; D017403:In Situ Hybridization; D008562:Membrane Glycoproteins / Q000737:chemistry*; D008969:Molecular Sequence Data; D016716:PC12 Cells; D051381:Rats; D016415:Sequence Alignment; D013570:Synaptic Membranes / Q000737:chemistry*; D014018:Tissue Distribution
chemical_list: D007136:Immunoglobulins; D008562:Membrane Glycoproteins; C548934:Nptn protein, rat; C103658:synaptic glycoprotein gp65