Cayabyab Francisco S, Schlichter Lyanne C
Division of Cellular and Molecular Biology, Toronto Western Research Institute, University Health Network and Department of Physiology, University of Toronto, Toronto, Ontario M5T 2S8, Canada.
J Biol Chem. 2002 Apr 19;277(16):13673-81. doi: 10.1074/jbc.M108211200. Epub 2002 Feb 7.
The human "ether-a-go-go"-related gene (HERG) K(+) channel, and its homologues are present in heart, neuronal tissue, some cancer cells, and the MLS-9 rat microglia cell line (Zhou, W., Cayabyab, F. S., Pennefather, P. S., Schlichter, L. C., and DeCoursey, T. E. (1998) J. Gen. Physiol. 111, 781-794). Despite its importance, there are few studies of ERG modulation. In this first report of regulation by tyrosine phosphorylation we show that MLS-9 cells express transcripts for r-erg1 (rat homologue of HERG) and r-erg2, and an immunoreactive doublet was identified using an anti-HERG antibody. The constitutive tyrosine phosphorylation of the ERG1 protein, detected by co-immunoprecipitation, was reduced by the protein-tyrosine kinase inhibitors, lavendustin A, herbimycin A, or genistein (but not daidzein). The whole cell ERG current was reduced by protein-tyrosine kinase inhibitors or the Src-selective inhibitory peptide, src40-58, but not by a scrambled peptide. Conversely, the current was increased by the Src-activating peptide, srcpY, but not by an inactive analogue. Activating endogenous Src or transfecting constitutively active v-Src altered the voltage dependence and deactivation kinetics to produce more current at negative potentials. Co-immunoprecipitation identified an association between the channel protein and Src. Thus, r-ERG1 and Src tyrosine kinase appear to exist in a signaling complex that is well positioned to modulate this K(+) channel and affect its contribution to cellular functions.
人类“快速激活延迟整流钾离子通道”相关基因（HERG）钾离子通道及其同源物存在于心脏、神经组织、某些癌细胞以及MLS-9大鼠小胶质细胞系中（周，W.，卡亚比亚布，F.S.，彭尼法瑟，P.S.，施利希特，L.C.，以及德库西，T.E.（1998年）《普通生理学杂志》111卷，781 - 794页）。尽管其很重要，但关于ERG调节的研究却很少。在这份关于酪氨酸磷酸化调节的首次报告中，我们表明MLS-9细胞表达r-erg1（HERG的大鼠同源物）和r-erg2的转录本，并且使用抗HERG抗体鉴定出一种免疫反应性双峰。通过免疫共沉淀检测到的ERG1蛋白的组成型酪氨酸磷酸化，被蛋白酪氨酸激酶抑制剂拉文达斯汀A、除草菌素A或染料木黄酮（而非大豆苷元）降低。全细胞ERG电流被蛋白酪氨酸激酶抑制剂或Src选择性抑制肽src40 - 58降低，但不被乱序肽降低。相反，电流被Src激活肽srcpY增加，但不被无活性类似物增加。激活内源性Src或转染组成型活性v-Src改变了电压依赖性和失活动力学，从而在负电位下产生更多电流。免疫共沉淀鉴定出通道蛋白与Src之间存在关联。因此，r-ERG1和Src酪氨酸激酶似乎存在于一个信号复合物中，该复合物处于良好位置来调节这种钾离子通道并影响其对细胞功能的贡献。
