Aifa Sami, Johansen Knut, Nilsson Ulrika K, Liedberg Bo, Lundström Ingemar, Svensson Samuel P S
Department of Pharmacology, Linköping University, SE-58185 Linköping, Sweden.
Cell Signal. 2002 Dec;14(12):1005-13. doi: 10.1016/s0898-6568(02)00034-7.
One early response to epidermal growth factor receptor (EGFR) activation is an increase in intracellular calcium. We have used surface plasmon resonance (SPR) to study real-time interactions between the intracellular juxtamembrane (JM) region of EGFR and calmodulin. The EGFR-JM (Met(644)-Phe(688)) was expressed as a GST fusion protein and immobilised on a sensor chip surface. Calmodulin specifically interacts with EGFR-JM in a calcium-dependent manner with a high on and high off rate. Chemical modification of EGFR-JM by using arginine-selective phenylglyoxal or deletion of the basic segment Arg(645)-Arg(657) inhibits the interaction. Phosphorylation of EGFR-JM by protein kinase C (PKC) or glutamate substitution of Thr(654) inhibits the interaction, suggesting that PKC phosphorylation electrostatically interferes with calmodulin binding to basic arginine residues. Calmodulin binding was also inhibited by suramin. Our results suggest that EGFR-JM is essential for epidermal growth factor (EGF)-mediated calcium-calmodulin signalling and for signal integration between other signalling pathways.
对表皮生长因子受体（EGFR）激活的一种早期反应是细胞内钙含量增加。我们利用表面等离子体共振（SPR）来研究EGFR细胞内近膜（JM）区域与钙调蛋白之间的实时相互作用。EGFR-JM（Met(644)-Phe(688)）表达为GST融合蛋白并固定在传感器芯片表面。钙调蛋白以钙依赖的方式与EGFR-JM特异性相互作用，结合和解离速率都很高。使用精氨酸选择性苯乙二醛对EGFR-JM进行化学修饰或缺失碱性片段Arg(645)-Arg(657)会抑制这种相互作用。蛋白激酶C（PKC）对EGFR-JM的磷酸化或Thr(654)的谷氨酸替代会抑制这种相互作用，这表明PKC磷酸化通过静电作用干扰钙调蛋白与碱性精氨酸残基的结合。苏拉明也会抑制钙调蛋白的结合。我们的结果表明，EGFR-JM对于表皮生长因子（EGF）介导的钙-钙调蛋白信号传导以及其他信号通路之间的信号整合至关重要。
