Kwan Lim G E, McNeill L, Whitley K, Becker D L, Zamoyska R
Molecular Immunology, National Institute for Medical Research, London, GB.
Eur J Immunol. 1998 Feb;28(2):745-54. doi: 10.1002/(SICI)1521-4141(199802)28:02<745::AID-IMMU745>3.0.CO;2-6.
CD8 is a T cell surface glycoprotein that participates in recognition of peptide/MHC class I molecules by binding to their alpha 3 domains. In addition, the cytoplasmic domain of CD8 associates with the intracellular tyrosine kinase p56(lck) (lck) promoting recruitment of lck to the TCR signaling complex. Recent data have suggested also that CD8 may interact with the TCR to promote energetically favorable conformations which increase its ligand binding. We have used the techniques of co-capping and confocal microscopy to ask whether we can detect an association between CD8 and the TCR independently of their binding to MHC class I molecules. We show that capping CD8 heterodimers with antibodies to the CD8 beta polypeptide is significantly more efficient than antibodies to the CD8 alpha polypeptide at inducing co-localization of TCR molecules with CD8, suggesting that there may be preferred conformations of CD8 which stabilize interactions with the TCR. In addition, we show by microscopy that intracellular lck redistributes very efficiently to the area of a CD8 cap, suggesting that there is a stronger association between lck and CD8 than has been proposed from immunoprecipitation analyses.
CD8是一种T细胞表面糖蛋白，它通过与肽/MHC I类分子的α3结构域结合参与对其的识别。此外，CD8的胞质结构域与细胞内酪氨酸激酶p56(lck)（lck）相关联，促进lck募集到TCR信号复合物中。最近的数据还表明，CD8可能与TCR相互作用，以促进能量上有利的构象，从而增加其配体结合。我们使用了共帽和共聚焦显微镜技术来研究是否能够检测到CD8与TCR之间的关联，而不依赖于它们与MHC I类分子的结合。我们发现，用针对CD8β多肽的抗体封闭CD8异二聚体，在诱导TCR分子与CD8共定位方面比针对CD8α多肽的抗体效率显著更高，这表明CD8可能存在优先构象，可稳定与TCR的相互作用。此外，我们通过显微镜观察发现，细胞内的lck非常有效地重新分布到CD8帽区域，这表明lck与CD8之间的关联比免疫沉淀分析所显示的更强。
