title: T cell receptor can be recruited to a subset of plasma membrane rafts, independently of cell signaling and attendantly to raft clustering.
abstract: The constitutive/inducible association of the T cell receptor (TCR) with isolated detergent-resistant, lipid raft-derived membranes has been studied in Jurkat T lymphocytes. Membranes resistant to 1% Triton X-100 contained virtually no CD3epsilon, part of the TCR complex, irrespective of cell stimulation. On the other hand, membranes resistant either to a lower Triton X-100 concentration (i.e. 0.2%) or to the less hydrophobic detergent Brij 58 (1%) contained (i) a low CD3epsilon amount (approximate 2.7% of total) in resting cells and (ii) a several times higher amount of the TCR component, after T cell stimulation with either antigen-presenting cells or with phytohemagglutinin. It appeared that CD3/TCR was constitutively associated with and recruited to a raft-derived membrane subset because (i) all three membrane preparations contained a similar amount of the raft marker tyrosine kinase Lck but no detectable amounts of the conventional membrane markers, CD45 phosphatase and transferrin receptor; (ii) a larger amount of particulate membranes were resistant to solubilization with 0.2% Triton X-100 and Brij 58 than to solubilization with 1% Triton X-100; and (iii) higher cholesterol levels were present in membranes resistant to either the lower Triton X-100 concentration or to Brij 58, as compared with those resistant to 1% Triton X-100. The recruitment of CD3 to the raft-derived membrane subset appeared (i) to occur independently of cell signaling events, such as protein-tyrosine phosphorylation and Ca(2+) mobilization/influx, and (ii) to be associated with clustering of plasma membrane rafts induced by multiple cross-linking of either TCR or the raft component, ganglioside GM(1). We suggest that during T cell stimulation a lateral reorganization of rafts into polarized larger domains can determine the recruitment of TCR into these domains, which favors a polarization of the signaling cascade.
authors.affiliation: Dipartimento di Fisiopatologia e Medicina Sperimentale, Università degli Studi di Siena, Viale Aldo Moro No. 1, 53100-Siena, Italy.
authors.forename: Emanuele
authors.initials: E
authors.lastname: Giurisato
authors.forename: Deirdre P
authors.initials: DP
authors.lastname: McIntosh
authors.forename: Maristella
authors.initials: M
authors.lastname: Tassi
authors.forename: Alessandra
authors.initials: A
authors.lastname: Gamberucci
authors.forename: Angelo
authors.initials: A
authors.lastname: Benedetti
mesh_terms: D015153:Blotting, Western; D017252:CD3 Complex; D002118:Calcium / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism*; D002592:Cetomacrogol / Q000494:pharmacology; D002784:Cholesterol / Q000378:metabolism; D003432:Cross-Linking Reagents / Q000494:pharmacology; D003902:Detergents / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D005677:G(M1) Ganglioside / Q000378:metabolism; D006801:Humans; D019169:Jurkat Cells; D017493:Leukocyte Common Antigens / Q000378:metabolism; D008027:Light; D021962:Membrane Microdomains; D017830:Octoxynol / Q000494:pharmacology; D010766:Phosphorylation; D017434:Protein Structure, Tertiary; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism*; D011990:Receptors, Transferrin / Q000378:metabolism; D012542:Scattering, Radiation; D015398:Signal Transduction; D013997:Time Factors; D014443:Tyrosine / Q000378:metabolism
chemical_list: D017252:CD3 Complex; C115335:CD3E protein, human; D003432:Cross-Linking Reagents; D003902:Detergents; D011948:Receptors, Antigen, T-Cell; D011990:Receptors, Transferrin; D005677:G(M1) Ganglioside; D014443:Tyrosine; D017830:Octoxynol; D002592:Cetomacrogol; D002784:Cholesterol; D017493:Leukocyte Common Antigens; D002118:Calcium