title: Profiling of the CD4 receptor complex proteins.
abstract: Intermolecular complexes produced by the CD4 molecule were studied. To preserve the integrity of weak protein-protein interactions of the CD4 antigen, cells were lysed in a mild nonionic detergent Brij97. Protein constituents of the complex were identified by our previously proposed fluorescence immunoprecipitation assay with subsequent mass spectrometry. In total, 26 proteins associated with CD4 were identified on CEM cells. The CD4 complex included the following major components: tyrosine phosphatase CD45, transferrin receptor CD71, tyrosine kinase Lck, and a lymphocyte phosphatase-associated phosphoprotein LPAP. The CD4 complex also contained some components of cytoskeleton and heat shock proteins. The association between CD4, CD71, and CD45 molecules was confirmed by immunoblotting. The CD4 complexes were not detected on the U937 myeloid cells lacking Lck and LPAP. We attempted to quantitatively characterize the CD4 complex composition.
authors.affiliation: National Research Center Institute of Immunology, Federal Biomedical Agency of Russia, Moscow, 115478, Russia. grkrotov@rambler.ru
authors.forename: G I
authors.initials: GI
authors.lastname: Krotov
authors.forename: M P
authors.initials: MP
authors.lastname: Krutikova
authors.forename: V G
authors.initials: VG
authors.lastname: Zgoda
authors.forename: A V
authors.initials: AV
authors.lastname: Filatov
mesh_terms: D015703:Antigens, CD / Q000302:isolation & purification; D015704:CD4 Antigens / Q000302:isolation & purification*; D002460:Cell Line; D003902:Detergents; D006801:Humans; D015151:Immunoblotting; D047468:Immunoprecipitation; D047908:Intracellular Signaling Peptides and Proteins / Q000302:isolation & purification; D017493:Leukocyte Common Antigens / Q000302:isolation & purification; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck) / Q000302:isolation & purification; D008565:Membrane Proteins / Q000302:isolation & purification; D046912:Multiprotein Complexes / Q000302:isolation & purification*; D040081:Protein Array Analysis; D025941:Protein Interaction Mapping; D011990:Receptors, Transferrin / Q000302:isolation & purification; D021241:Spectrometry, Mass, Electrospray Ionization; D053719:Tandem Mass Spectrometry; D020298:U937 Cells
chemical_list: D015703:Antigens, CD; D015704:CD4 Antigens; C068126:CD71 antigen; D003902:Detergents; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D046912:Multiprotein Complexes; C090519:PTPRCAP protein, human; D011990:Receptors, Transferrin; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); D017493:Leukocyte Common Antigens; C516769:PTPRC protein, human