Isakov N
Department of Microbiology and Immunology, Faculty of Health Sciences, Ben Gurion University of the Negev, Beer Sheva, Israel.
Immunol Res. 1997 Feb;16(1):85-100. doi: 10.1007/BF02786325.
The initial stages of an immune response are regulated at the level of the cell-surface antigen and Fc receptors. The extracellular portions of these receptors provide immune specificity and determine the nature of the responding effector cells, whereas the intracellular portion transduces signals into the cell and determines the intensity and duration of the immune response. Recent studies led to the identification of two types of modules within the cytoplasmic region of receptor subunits that are critical for the activation and termination of signal transduction pathways. Phosphorylation of the conserved tyrosine residues within the two modules, the immunoreceptor tyrosine-based activation motif (ITAM) and the immunoreceptor tyrosine-based inhibition motif (ITIM), is followed by the recruitment of different sets of SH2-containing molecules to the receptor site. These proteins regulate the receptor-linked signal transduction pathways in a positive or a negative fashion, which is a reminiscent of the ancestral Yin-Yang principle.
免疫反应的初始阶段在细胞表面抗原和Fc受体水平受到调控。这些受体的细胞外部分提供免疫特异性并决定应答效应细胞的性质，而细胞内部分则将信号转导至细胞内并决定免疫反应的强度和持续时间。最近的研究发现受体亚基胞质区域内有两种类型的模块，它们对于信号转导途径的激活和终止至关重要。两种模块即基于免疫受体酪氨酸的激活基序（ITAM）和基于免疫受体酪氨酸的抑制基序（ITIM）内保守酪氨酸残基的磷酸化，随后会有不同组含SH2的分子被招募至受体位点。这些蛋白质以正向或负向方式调节受体相关的信号转导途径，这让人联想到古老的阴阳原则。
