Michiel D F, Garcia G G, Evans G A, Farrar W L
Laboratory of Molecular Immunoregulation, National Cancer Institute, Frederick Cancer Research and Development Center, MD 21702-1201.
Cytokine. 1991 Sep;3(5):428-38. doi: 10.1016/1043-4666(91)90047-h.
Interleukin 2 (IL-2) has been shown to stimulate tyrosine phosphorylation of a number of proteins requiring only the p75 beta chain of the IL-2 receptor. Unlike the receptors for epidermal growth factor, insulin, and other growth factors, the p55-alpha and p75-beta chains of the IL-2 receptor have no tyrosine protein kinase domain suggesting that the IL-2 receptor complex activates protein kinases by a unique mechanism. The activation of tyrosine kinases by IL-2 in situ was studied and using a novel methodology has shown tyrosine kinase activity associated with the purified IL-2R complex in vitro. IL-2 stimulated the in situ tyrosine phosphorylation of 97 kDa and 58 kDa proteins which bound to poly(Glu,Tyr)4:1, a substrate for tyrosine protein kinases, suggesting these proteins had characteristics found in almost all tyrosine kinases. IL-2 was found to stimulate tyrosine protein kinase activity in receptor extracts partially purified from human T lymphocytes and the YT cell line. Biotinylated IL-2 was used to precipitate the high-affinity-receptor complex and phosphoproteins associated with it. The data indicated that the 97-kDa and 58-kDa phosphotyrosyl proteins were tightly associated with the IL-2 receptor complex. These proteins were phosphorylated on tyrosine residues by IL-2 stimulation of intact cells and ligand treatment of in vitro receptor extracts. Furthermore, the 97-kDa and 58-kDa proteins were found in streptavidin-agarose/biotinylated IL-2 purified receptor preparations and showed high affinity for tyrosine kinase substrate support matrixes. The experiments suggest that these two proteins are potential candidates for tyrosine kinases involved in the IL-2R complex signal transduction process.
白细胞介素2（IL-2）已被证明可刺激多种仅需要IL-2受体p75β链的蛋白质发生酪氨酸磷酸化。与表皮生长因子、胰岛素及其他生长因子的受体不同，IL-2受体的p55-α链和p75-β链没有酪氨酸蛋白激酶结构域，这表明IL-2受体复合物通过独特机制激活蛋白激酶。对IL-2在原位激活酪氨酸激酶进行了研究，采用一种新方法已显示体外纯化的IL-2R复合物具有酪氨酸激酶活性。IL-2刺激了与聚（Glu，Tyr）4:1（酪氨酸蛋白激酶的一种底物）结合的97 kDa和58 kDa蛋白质的原位酪氨酸磷酸化，提示这些蛋白质具有几乎所有酪氨酸激酶所具备的特征。发现IL-2可刺激从人T淋巴细胞和YT细胞系部分纯化的受体提取物中的酪氨酸蛋白激酶活性。生物素化的IL-2用于沉淀高亲和力受体复合物及其相关的磷蛋白。数据表明97 kDa和58 kDa的磷酸酪氨酸蛋白与IL-2受体复合物紧密相关。这些蛋白质在完整细胞经IL-2刺激以及体外受体提取物经配体处理后，其酪氨酸残基发生磷酸化。此外，在抗生物素蛋白-琼脂糖/生物素化IL-2纯化的受体制剂中发现了97 kDa和58 kDa蛋白质，且它们对酪氨酸激酶底物支持基质具有高亲和力。这些实验提示这两种蛋白质是参与IL-2R复合物信号转导过程的酪氨酸激酶的潜在候选者。
