J Immunol. 2010 Sep 1;185(5):2645-9.
The CD4 (T4) antigen is a cell-surface glycoprotein that is expressed predominantly on the surface of helper T cells and has been implicated in the regulation of T-cell activation and in the associative recognition of class II antigens of the major histocompatibility complex. In addition, the CD4 antigen appears to serve as a receptor for the human immunodeficiency virus (HIV). An important question has been whether the CD4 receptor is linked to an intracellular mediator that could regulate the activation of the CD4 subset. In this paper, we provide preliminary evidence that the CD4 receptor is complexed in detergent lysates to a protein-tyrosine kinase (PTK) of 55–60 kDa, which is expressed specifically in T cells. The PTK is the human analogue of the murine pp56 (pp56) and has significant homology with c-, c-, and other members of the family. The identification of the PTK associated with CD4 receptor was made by use of an antiserum to a synthetic peptide that was deduced from the DNA sequence of PTK. Two-dimensional nonequilibrium pH gradient gel electrophoresis/NaDodSO/PAGE revealed the kinase to focus as a heterogeneous collection of spots in the pH range of 4.0–5.0. Furthermore, phosphorylation revealed the phosphorylation of two additional polypeptides at 40 and 80 kDa, in addition to the autophosphorylation of the PTK at 55–60 kDa. The potential importance of the association between the CD4 receptor and the PTK of T cells is discussed in relation to T-cell activation and HIV infectivity.
CD4(T4)抗原是一种细胞表面糖蛋白,主要表达于辅助性 T 细胞表面,与 T 细胞的激活调控以及主要组织相容性复合体Ⅱ类抗原的协同识别有关。此外,CD4 抗原似乎是人类免疫缺陷病毒(HIV)的受体。一个重要的问题是,CD4 受体是否与一种细胞内介质相连,这种介质可以调节 CD4 亚群的激活。本文提供了初步证据,表明 CD4 受体在去污剂裂解物中与一种 55-60 kDa 的蛋白酪氨酸激酶(PTK)复合,该激酶仅在 T 细胞中表达。PTK 是鼠 pp56(pp56)的人类类似物,与 c-、c-和其他家族成员有显著同源性。与 CD4 受体相关的 PTK 的鉴定是通过使用针对从 PTK 的 DNA 序列推导的合成肽的抗血清进行的。二维非平衡 pH 梯度凝胶电泳/NaDodSO/PAGE 显示,激酶在 pH 值为 4.0-5.0 的范围内聚焦为一系列不均匀的斑点。此外,磷酸化反应显示,除了 55-60 kDa 的 PTK 自身磷酸化外,还可磷酸化另外两条 40 和 80 kDa 的多肽。CD4 受体与 T 细胞的 PTK 之间的关联与 T 细胞的激活和 HIV 感染性有关,其潜在重要性正在讨论中。