Geisler C
Department of Tumor Cell Biology, Fibiger Institute, Copenhagen, Denmark.
J Immunol. 1992 Apr 15;148(8):2437-45.
The TCR consists of the Ti alpha beta heterodimer and the associated CD3 chains, CD3 gamma delta epsilon zeta 2 or zeta eta. The structural relationships between the subunits of the Ti/CD3 complex are still not fully understood. To explore the roles of the individual CD3 chains for the assembly, intracellular processing, and expression of the TCR, mutants of the T cell line Jurkat were isolated. One variant, JGN, was found to produce all the Ti/CD3 components with the exception of CD3-gamma. The results indicate that: 1) the tetrameric form (Ti alpha beta-CD3 delta epsilon) of the Ti/CD3 complex is produced in the endoplasmic reticulum in the absence of CD3-gamma; 2) CD3-zeta does not associate with the Ti alpha beta-CD3 delta epsilon complex; 3) the Ti alpha beta-CD3 delta epsilon complex is not exported from the endoplasmic reticulum to the Golgi apparatus; and 4) CD3-gamma is required for cell surface expression of the Ti/CD3 complex. Transfection of the wild-type CD3-gamma gene into JGN reconstituted expression of functional Ti/CD3 complexes, and analysis of T cell lines producing different amounts of CD3-gamma indicated that CD3-gamma and CD3-delta competed for the binding to CD3-epsilon.
T细胞受体（TCR）由Tiαβ异二聚体和相关的CD3链（CD3γδεζ2或ζη）组成。Ti/CD3复合物各亚基之间的结构关系仍未完全明确。为了探究各个CD3链在TCR装配、细胞内加工及表达过程中的作用，我们分离出了T细胞系Jurkat的突变体。发现其中一个变体JGN能产生除CD3-γ之外的所有Ti/CD3组分。结果表明：1）在没有CD3-γ的情况下，内质网中会产生Ti/CD3复合物的四聚体形式（Tiαβ-CD3δε）；2）CD3-ζ不与Tiαβ-CD3δε复合物结合；3）Tiαβ-CD3δε复合物不会从内质网转运至高尔基体；4）Ti/CD3复合物的细胞表面表达需要CD3-γ。将野生型CD3-γ基因转染到JGN中可重建功能性Ti/CD3复合物的表达，对产生不同量CD3-γ的T细胞系进行分析表明，CD3-γ和CD3-δ竞争与CD3-ε的结合。
