Kim K M, Reth M
Max-Planck Institut für Immunobiologie, Freiburg, Germany.
Immunol Lett. 1995 Jan;44(2-3):81-5. doi: 10.1016/0165-2478(94)00219-h.
Most mature B lymphocytes co-express two classes of antigen receptor, IgM and IgD. The differences in the signal transduction from the 2 receptors are still a matter of controversy. We have analysed B-cell lines expressing IgM or IgD antigen receptors with the same antigen specificity. Cross-linking of these receptors with either antigen or class-specific antibodies results in the activation of protein tyrosine kinases and the phosphorylation of the same substrate proteins. The kinetics and intensity of phosphorylation, however, were quite different between the 2 receptors when they were cross-linked by antigen. In membrane IgM-expressing cells, the substrate phosphorylation reached a maximum already after 1 min and diminished after 60 min whereas in the membrane IgD-expressing cells, the substrate phosphorylation increases further over time, reached its maximum at 60 min and persisted longer than 240 min after exposure to antigen. Recently prolonged signaling has been found to be responsible for signaling differences between tyrosine kinase receptors using otherwise similar signaling routes. Thus, the duration of a signal may be an important biological feature of signal transducing cascades.
大多数成熟的B淋巴细胞共表达两类抗原受体，即IgM和IgD。这两种受体信号转导的差异仍存在争议。我们分析了表达具有相同抗原特异性的IgM或IgD抗原受体的B细胞系。用抗原或类特异性抗体使这些受体交联会导致蛋白酪氨酸激酶激活以及相同底物蛋白的磷酸化。然而，当这两种受体被抗原交联时，磷酸化的动力学和强度有很大差异。在表达膜IgM的细胞中，底物磷酸化在1分钟后就达到最大值，并在60分钟后减弱；而在表达膜IgD的细胞中，底物磷酸化随时间进一步增加，在60分钟时达到最大值，并在接触抗原后持续超过240分钟。最近发现，使用其他类似信号通路的酪氨酸激酶受体之间的信号差异与信号延长有关。因此，信号的持续时间可能是信号转导级联反应的一个重要生物学特征。
