title: Tetraspanins connect several types of Ig proteins: IgM is a novel component of the tetraspanin web on B-lymphoid cells.
abstract: The tetraspanins form a family of about 30 molecules mainly expressed on the cell surface. They have been reported to be involved in many physiological or pathological processes, such as fertilization, immune response, development of the nervous system, and metastasis, as well as in infectious diseases (HCV, malaria, etc.). The tetraspanins may play a role as "organizers" of multimolecular complexes on the cell surface associating numerous proteins, the "tetraspanin web." To better define the composition of the tetraspanin web, its characterization has been recently performed using mass spectrometry and proteomics. We report the proteomic analysis of tetraspanin complexes on B-lymphoid cells. Immunoprecipitation experiments were performed using mAbs directed against the tetraspanin CD9, and associated molecules were identified by MALDI-TOF (matrix assisted laser desorption ionization time of flight) mass spectrometry. This led to the identification of IgM as a novel component of the complexes. Thus, tetraspanins may connect several types of proteins with Ig domains, including HLA-DR, EWI-2, and IgM, that may play a role in immune responses.
authors.affiliation: INSERM U268 Institut André-Lwoff, Université Paris XI, Hôpital Paul-Brousse, 94807, Villejuif Cedex, France. flenaour@vjf.inserm.fr
authors.forename: François
authors.initials: F
authors.lastname: Le Naour
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Charrin
authors.forename: Valérie
authors.initials: V
authors.lastname: Labas
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Le Caer
authors.forename: Claude
authors.initials: C
authors.lastname: Boucheix
authors.forename: Eric
authors.initials: E
authors.lastname: Rubinstein
mesh_terms: D017951:Antigen Presentation; D015703:Antigens, CD / Q000502:physiology*; D001402:B-Lymphocytes / Q000276:immunology*; D006801:Humans; D007075:Immunoglobulin M / Q000502:physiology*; D008562:Membrane Glycoproteins / Q000502:physiology*; D040901:Proteomics; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D060245:Tetraspanin 29
chemical_list: D015703:Antigens, CD; C554869:CD9 protein, human; D007075:Immunoglobulin M; D008562:Membrane Glycoproteins; D060245:Tetraspanin 29