title: Transmembrane-4 superfamily proteins CD81 (TAPA-1), CD82, CD63, and CD53 specifically associated with integrin alpha 4 beta 1 (CD49d/CD29).
abstract: Anti-alpha 4 integrin mAb coprecipitated CD81 (TAPA-1), a 25-kDa cell surface protein, from various alpha 4 beta1 -positive hemopoietic cell lines, including Molt4, Jurkat, Ramos, and alpha 4-transfected K562 (KX4C4) cells. In reciprocal experiments, the integrin alpha 4 beta 1 (VLA4, CD49d/CD29) could be reprecipitated from CD81 immunoprecipitates. Anti-alpha 4 integrin mAb also coprecipitated CD81 from the alpha 4 beta 7-positive B cell line RPMI 8866. In contrast, no CD81 was identified in alpha 2 beta 1, alpha 5 beta 1, or alpha L beta 2 immunoprecipitates. Abs to other members of the transmembrane-4 superfamily, including CD53, CD63, and CD82, also coprecipitated alpha 4 beta 1. As shown by confocal microscopy, CD81 and CD82 colocalized with alpha 4 beta 1 in cell surface clusters. The cytoplasmic domain of the alpha 4 integrin was not necessary for alpha 4 beta 1/CD81 association, nor was the association influenced by divalent cations, EDTA, integrin-activating mAb, or alpha 4 subunit cleavage. Notably, two independent alpha 4 adhesion-deficient mutants (D346E and D408E) were deficient in their ability to associate with CD81. Thus, CD81 and other transmembrane-4 superfamily members may participate in functionally relevant interactions with alpha 4 beta 1 and other integrins.
authors: Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02115, USA.
authors: B A
authors: BA
authors: Mannion
authors: F
authors: F
authors: Berditchevski
authors: S K
authors: SK
authors: Kraeft
authors: L B
authors: LB
authors: Chen
authors: M E
authors: ME
authors: Hemler
mesh_terms: D000911:Antibodies, Monoclonal / Q000494:pharmacology; D015703:Antigens, CD / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D000945:Antigens, Differentiation, T-Lymphocyte / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D002448:Cell Adhesion / Q000276:immunology; D002460:Cell Line; D006801:Humans; D039041:Integrin alpha4beta1; D016023:Integrins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D051861:Kangai-1 Protein; D008562:Membrane Glycoproteins / Q000235:genetics / Q000276:immunology* / Q000302:isolation & purification / Q000378:metabolism*; D008565:Membrane Proteins; D008970:Molecular Weight; D009154:Mutation; D010980:Platelet Membrane Glycoproteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D011518:Proto-Oncogene Proteins; D016201:Receptors, Lymphocyte Homing / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D060265:Tetraspanin 25; D060225:Tetraspanin 28; D060149:Tetraspanin 30
chemical_list: D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; C554894:CD53 protein, human; C554586:CD63 protein, human; C554798:CD81 protein, human; C497688:CD82 protein, human; D039041:Integrin alpha4beta1; D016023:Integrins; D051861:Kangai-1 Protein; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D010980:Platelet Membrane Glycoproteins; D011518:Proto-Oncogene Proteins; D016201:Receptors, Lymphocyte Homing; D060265:Tetraspanin 25; D060225:Tetraspanin 28; D060149:Tetraspanin 30