Koning F, Lew A M, Maloy W L, Valas R, Coligan J E
Biological Resources Branch, National Institute of Allergy and Infectious Diseases, Bethesda, MD 20892.
J Immunol. 1988 May 1;140(9):3126-34.
The biosynthesis, processing, and assembly of the TCR alpha- and beta-chains with each other and with the CD3 complex were investigated on both cell surface positive (TCR+CD3-) and negative (TCR-CD3-) cell lines. The results indicate that 1) in cell surface TCR-CD3- cell lines (MOLT 3, CCRF-CEM), TCR-beta, but not alpha-chains are present intracellularly. TCR-beta-CD3 complexes are readily found in these cell lines, but no evidence for final processing or cell surface expression of such incomplete TCR-CD3 complexes is observed. 2) In the cell surface TCR+CD3+ cell line HPB-ALL, both alpha- and beta-chains are present intracellularly. Whereas non-glycosylated forms of TCR-beta chain can be detected, only more mature forms of TCR alpha-chains are detected indicating that the alpha-chains are more rapidly glycosylated than the beta-chains. 3) The large majority of the intracellular alpha- and beta-chains is not disulfide linked and a small fraction of these is associated with CD3. 4) Only small amounts of the total intracellular TCR chains are found as CD3-associated disulfide-linked alpha beta-heterodimers. 5) Final processing of TCR chains for cell surface expression takes place after formation of these TCR-alpha beta-CD3 complexes. Thus, both the TCR alpha- and beta-chains are over-produced and only relatively small amounts of these chains form CD3-associated heterodimers that are processed for cell surface expression. Analogous results were obtained with a non-leukemic CTL clone. Based on these observations, a model for the biosynthesis and assembly of the TCR-CD3 complex is presented.
在细胞表面阳性（TCR+CD3-）和阴性（TCR-CD3-）细胞系中，研究了TCRα链和β链彼此之间以及与CD3复合物的生物合成、加工和组装。结果表明：1）在细胞表面TCR-CD3-细胞系（MOLT 3、CCRF-CEM）中，细胞内存在TCR-β链，但不存在α链。在这些细胞系中很容易发现TCR-β-CD3复合物，但未观察到此类不完全TCR-CD3复合物进行最终加工或细胞表面表达的证据。2）在细胞表面TCR+CD3+细胞系HPB-ALL中，细胞内同时存在α链和β链。虽然可以检测到TCR-β链的非糖基化形式，但仅检测到更成熟形式的TCRα链，这表明α链比β链更快地进行糖基化。3）细胞内绝大多数α链和β链没有通过二硫键连接，其中一小部分与CD3相关。4）在总的细胞内TCR链中，只有少量以与CD3相关的二硫键连接的αβ异二聚体形式存在。5）TCR链进行细胞表面表达的最终加工发生在这些TCR-αβ-CD3复合物形成之后。因此，TCRα链和β链均过量产生，只有相对少量的这些链形成与CD3相关的异二聚体，这些异二聚体经过加工后进行细胞表面表达。用一个非白血病CTL克隆也获得了类似的结果。基于这些观察结果，提出了一个TCR-CD3复合物生物合成和组装的模型。
