Human CD8β, but not mouse CD8β, can be expressed in the absence of CD8α as a ββ homodimer
Human CD8β, but not mouse CD8β, can be expressed in the absence of CD8α as a ββ homodimer
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DOI：
10.4049/jimmunol.164.2.833
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发表时间：
2000-01-15
影响因子：
4.4
通讯作者：
Kavathas, PB
中科院分区：
文献类型：
--
作者：
Devine, L;Kieffer, LJ;Kavathas, PB
T细胞辅助受体CD 8作为CD 8 α多肽链的二硫键连接的同源二聚体和CD 8 α-和CD 8 β-链的异源二聚体存在于成熟T细胞上。CD 8 α-链结合I类MHC并与酪氨酸激酶p56（lck）结合的功能用CD 8 α α同源二聚体证明，CD 8 α-链作为更好的辅助受体发挥作用，但CD 8 β的实际功能并不那么清楚。解决这一问题受到CD 8 β在没有CD 8 α的情况下明显不能表达的阻碍。该研究表明，在转染的COS-7细胞和鼠淋巴细胞中，人而不是小鼠的CD 8 β可以在没有CD 8 α的细胞表面上表达。通过构建嵌合蛋白，我们发现小鼠CD 8 β的IG结构域是导致小鼠CD 8 β二聚体表达缺失的原因。与CD 8 α α相反，在细胞-细胞粘附试验中，CD 8 β β不能结合MHC I类。这种形式的CD 8的检测应有助于CD 8 β链功能的研究，并表明在解释使用具有鼠CD 8 β β IG结构域的嵌合蛋白进行的CDS功能研究时应谨慎。此外，我们证明了CD 8 α的IG结构域也参与控制CD 8表达的能力。CD 8 α中B-和F-链半胱氨酸残基的突变降低了蛋白质正确折叠的能力，因此，表达的能力。
The T cell coreceptor CD8 exists on mature T cells as disulfide-linked homodimers of CD8 alpha polypeptide chains and heterodimers of CD8 alpha- and CD8 beta-chains, The function of the CD8 alpha-chain for binding to MHC class I and associating with the tyrosine kinase p56(lck) was demonstrated with CD8 alpha alpha homodimers, CD8(UP functions as a better coreceptor, but the actual function of CD8 beta is less dear. Addressing this issue has been hampered by the apparent inability of CD8 beta to be expressed without CD8 alpha. This study demonstrates that human, but not mouse, CD8 beta can be expressed on the cell surface without CD8 alpha in both transfected COS-7 cells and murine lymphocytes. By creating chimeric proteins, we show that the murine Ig domain of CD8 beta is responsible for the lack of expression of murine CD8 beta beta dimers, In contrast to CD8 alpha alpha, CD8 beta beta is unable to bind MHC class I in a cell-cell adhesion assay. Detection of this form of CD8 should facilitate studies on the function of the CD8 beta-chain and indicates that caution should be used when interpreting studies on CDS function using chimeric protein with the murine CD8 beta beta Ig domain. In addition, we demonstrate that the Ig domains of CD8 alpha are also involved in controlling the ability of CD8 to be expressed, Mutation of B- and F-strand cysteine residues in CD8 alpha reduced the ability of the protein to fold properly and, therefore, to be expressed.