期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1990
卷号：87
期号：18
页码：7220-7224
DOI：10.1073/pnas.87.18.7220
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The T-cell antigen receptor (TCR) consists of heterodimeric glycoproteins (TCR alpha beta or gamma delta) that demonstrate homology with immunoglobulins. Noncovalently associated with the alpha beta (or gamma delta) heterodimer are at least five nonvariant proteins (CD3-gamma, -delta, -epsilon, -zeta, and -eta), which together comprise the TCR-CD3 complex. The stoichiometry of the antigen receptor has been assumed to be either alpha beta gamma delta epsilon zeta zeta or alpha beta gamma delta epsilon zeta eta. In this paper we provide several lines of evidence that support the notion that the mature TCR-CD3 complex on the cell surface contains two CD3-epsilon polypeptide chains. Transfection of two murine T cell-T cell hybridomas with the human DNA encoding CD3-epsilon protein demonstrated that both murine and human CD3-epsilon chains were present within the same TCR-CD3 complex. Analysis of thymocytes isolated from transgenic mice that expressed high copy numbers of the human CD3-epsilon gene showed that the heterologous human CD3-epsilon subunits were coexpressed with murine CD3-epsilon in the same TCR-CD3 complex. Since CD3-epsilon was shown to form disulfide-linked homodimers both in human and murine T cells, the two CD3-epsilon subunits present in the TCR-CD3 complex were in direct contact with one another. The presence of two CD3-epsilon polypeptide chains in close proximity to one another in the TCR-CD3 complex may have important implications for its assembly and its signal transduction mechanisms.
