Alam R, Pazdrak K, Stafford S, Forsythe P
University of Texas Medical Branch, Department of Internal Medicine, Galveston 77555-0762, USA.
Int Arch Allergy Immunol. 1995 May-Jun;107(1-3):226-7. doi: 10.1159/000236985.
We have shown that the interaction of interleukin (IL)-5 with the receptor activates Lyn tyrosine kinase within 1 min and Jak2 tyrosine kinase within 1-3 min. IL-5 also stimulates GTP binding to p21ras. The signal is subsequently propagated through the activation of Raf-1, MEK, and MAP kinases as shown by their increased autophosphorylation in vitro and phosphorylation in situ. Jak2 kinase has been shown to phosphorylate STAT nuclear proteins. The activation of STAT nuclear factors was studied by electrophoretic mobility shift assay using a gamma activation site (GAS) probe. We found that IL-5 induces two GAS-binding proteins in eosinophils, one of which is STAT1. We conclude that IL-5 induced signals are propagated through two distinct pathways: (1) Lyn-->Ras-->Raf-1-->MEK-->MAP kinase and (2) Jak2-->STAT1.
我们已经证明，白细胞介素（IL）-5与受体的相互作用在1分钟内激活Lyn酪氨酸激酶，在1 - 3分钟内激活Jak2酪氨酸激酶。IL-5还刺激GTP与p21ras结合。随后，信号通过Raf-1、MEK和MAP激酶的激活而传播，这在体外其自身磷酸化增加和原位磷酸化中得到证实。已证明Jak2激酶可磷酸化STAT核蛋白。通过使用γ激活位点（GAS）探针的电泳迁移率变动分析研究STAT核因子的激活。我们发现IL-5在嗜酸性粒细胞中诱导两种GAS结合蛋白，其中一种是STAT1。我们得出结论，IL-5诱导的信号通过两条不同的途径传播：（1）Lyn→Ras→Raf-1→MEK→MAP激酶和（2）Jak2→STAT1。
