A fraction of CD3 epsilon subunits exists as disulfide-linked dimers in both human and murine T lymphocytes

In a T cell antigen receptor complex (TCR), the clonotypic disulfide-linked Ti heterodimer is noncovalently associated with the invariant CD3 polypeptides. The latter are composed of three monomeric subunits (gamma, delta, epsilon) and either a disulfide-linked homodimer (zeta zeta) or a disulfide-l...

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Bibliographic Details
Published in:The Journal of biological chemistry 1990-09, Vol.265 (26), p.15850-15853
Main Authors: JIN, Y.-J, KOYASU, S, MOINGEON, P, STEINBRICH, R, TARR, G. E, REINHERZ, E. L
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Animals
Antigens, CD - isolation & purification
Antigens, Differentiation, T-Lymphocyte - isolation & purification
Biological and medical sciences
CD3 Complex
Cell Line
Disulfides - analysis
Electrophoresis, Gel, Two-Dimensional
Electrophoresis, Polyacrylamide Gel
Fundamental and applied biological sciences. Psychology
Fundamental immunology
Humans
Immunobiology
Lymphoid cells: ontogeny, maturation, markers, receptors, circulation and recirculation
Macromolecular Substances
Membrane Glycoproteins - isolation & purification
Mice
Molecular Sequence Data
Molecular Weight
Peptide Fragments - isolation & purification
Receptors, Antigen, T-Cell - isolation & purification
T-Lymphocytes - immunology
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Summary:In a T cell antigen receptor complex (TCR), the clonotypic disulfide-linked Ti heterodimer is noncovalently associated with the invariant CD3 polypeptides. The latter are composed of three monomeric subunits (gamma, delta, epsilon) and either a disulfide-linked homodimer (zeta zeta) or a disulfide-linked heterodimer (zeta eta). The exact stoichiometry of the Ti-CD3 subunits in a given complex is still largely unknown. Here, we report the presence of a CD3 epsilon dimer in a fraction of the TCR. When TCRs from both human and murine T lymphocytes were immunoprecipitated with monoclonal antibodies against either CD3 epsilon or Ti, a 40-kDa disulfide-linked dimer was coprecipitated with the other TCR subunits from digitonin lysates. Amino acid sequence analysis of peptides obtained by in situ CNBr cleavage of the 20-kDa product blotted to polyvinyl difluoride membranes from reducing/nonreducing two-dimensional gels identified human CD3 epsilon. Assuming this CD3 epsilon to derive from a homodimer, then either some TCRs contain more than one CD3 epsilon chain or several TCRs are covalently associated with one another via their CD3 epsilon subunits. Although it has been suggested that a putative TCR association with CD2 exists under similar conditions to those utilized to detect CD3 epsilon dimers, the CD2 molecule was not coimmunoprecipitated with the TCR by any of a series of anti-CD3 epsilon monoclonal antibodies. In conjunction with the fact that CD2 and the TCR do not colocalize during conjugate formation between T cells and antigen-presenting cells (Koyasu, S., Lawton, T., Novick, D., Recny, M. A., Siliciano, R. F., Wallner, B. P., and Reinherz, E. L. (1990) Proc. Natl. Acad. Sci. U. S. A. 87, 2603-2607), we conclude that CD2 and the TCR are not physically associated on the T cell surface.
ISSN:0021-9258
1083-351X
DOI:10.1016/S0021-9258(18)55476-4