Molecular associations between the T-lymphocyte antigen receptor complex and the surface antigens CD2, CD4, or CD8 and CD5.

The T-cell antigen receptor (TCR) complex is the key structure involved in signal transduction in T cells. To analyze associations between the TCR complex and other molecules, immunoprecipitations were carried out, followed by phosphorylation of molecules in vitro by tyrosine kinases associated with the precipitated molecules. This provided a sensitive assay for molecular complexes, and associations were demonstrated between the TCR complex and the surface antigens CD2, CD4, or CD8 and CD5 in normal rat T cells. The complexes were readily seen in immunoprecipitates from Brij 96 but not Nonidet P-40 detergent extracts. The multimolecular complexes are associated with the internal tyrosine kinases p56lck and p59fyn. The presence of p56lck associated with CD4 or CD8 was also examined in early thymocytes, natural killer cells, and macrophages. The kinase was present in all cases except that of normal macrophages. IMAGES:

T细胞抗原受体（T-cell antigen receptor, TCR）复合物是T细胞内参与信号转导（signal transduction）的关键结构。为探究TCR复合物与其他分子间的相互关联，研究人员开展了免疫沉淀（immunoprecipitation）实验，随后借助与沉淀分子结合的酪氨酸激酶（tyrosine kinases）在体外（in vitro）对靶分子进行磷酸化修饰。该方法为分子复合物的检测提供了高灵敏度的分析手段，研究证实正常大鼠T细胞中，TCR复合物可与表面抗原CD2、CD4、CD8及CD5形成稳定的分子关联复合物。这类多分子复合物可在Brij 96去垢剂提取的免疫沉淀产物中被清晰观测到，但在Nonidet P-40去垢剂提取的样本中无法检出。该多分子复合物可与胞内酪氨酸激酶p56lck及p59fyn相结合。研究同时检测了早期胸腺细胞、自然杀伤细胞及巨噬细胞中与CD4或CD8结合的p56lck的表达情况，结果显示除正常巨噬细胞外，其余受试样本中均检测到该激酶的存在。
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