Kinetic model for FGF, FGFR, and proteoglycan signal transduction complex assembly
Kinetic model for FGF, FGFR, and proteoglycan signal transduction complex assembly
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DOI：
10.1021/bi0352320
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发表时间：
2004-04-27
期刊：
影响因子：
2.9
通讯作者：
Linhardt, RJ
中科院分区：
文献类型：
--
作者：
Ibrahimi, OA;Zhang, FM;Linhardt, RJ
成纤维细胞生长因子受体（FGFR）二聚化和活化的当前工作模型需要成纤维细胞生长因子（FGF）、FGFR和肝素或硫酸乙酰肝素蛋白聚糖（HSPG）的三元复合物在质膜上的组装。最近的FGF 2-FGFR 1-肝素晶体结构提供了FGF-FGFR-肝素复合物的详细但静态的视图。然而，三元配合物组装的动力学还有待研究。在这里，我们使用表面等离子体共振（SPR）表征FGF 2，FGFR 1和肝素的相互作用。二元FGF 2/FGFR 1（K-D = 62 nM）、FGF 2/肝素（K-D = 39 nM）和FGFR 1/肝素（K-D = 3.2 μ M）相互作用的结合常数与在FGF 2-FGFR 1-肝素晶体结构中观察到的结合界面的大小相关。有趣的是，将FGF 2和FGFR 1顺序注射和等摩尔FGF 2-FGFR 1注射到肝素新蛋白聚糖表面上的传感图的比较表明，FGF 2显著增强了FGFR 1与肝素的缔合，并使我们提出了三元FGF-FGFR-HSPG复合物逐步组装的模型。FGFR 1-肝素相互作用的弱结合亲和力表明在该模型中。FGFR和HSPG在不存在FGF配体的情况下是未结合的。FGF的可用性导致初始FGF-HSPG复合物的形成，其促进FGFR的快速结合并产生能够经历二聚化和随后的FGFR活化的三元复合物。相比之下，二元FGF-FGFR或FGFR-HSPG复合物为中间体的三元复合物的动力学组装的替代模型与实验数据不一致。
The current working model for fibroblast growth factor receptor (FGFR) dimerization and activation requires the assembly of a ternary complex of fibroblast growth factor (FGF), FGFR, and heparin or heparan sulfate proteoglycan (HSPG) on the plasma membrane. The recent FGF2-FGFR1-heparin crystal structure provides a detailed but static view of the FGF-FGFR-heparin complex. However, the kinetics of ternary complex assembly has yet to be investigated. Here, we characterize FGF2, FGFR1, and heparin interactions using surface plasmon resonance (SPR). Binding constants for binary FGF2/FGFR1 (K-D = 62 nM), FGF2/heparin (K-D = 39 nM), and FGFR1/heparin (K-D = 3.2 muM) interactions correlate to the magnitude of binding interface observed in the FGF2-FGFR1-heparin crystal structure. Interestingly, comparison of sensorgrams of sequential injections of FGF2 and FGFR1 and equimolar FGF2-FGFR1 injections onto a heparin neoproteoglycan surface demonstrates that FGF2 dramatically enhances the association of FGFR1 with heparin and leads us to propose a model for the stepwise assembly of a ternary FGF-FGFR-HSPG complex. The weak binding affinity of the FGFR1-heparin interaction suggests that in this model. FGFR and HSPG are unbound in the absence of FGF ligand. The availability or FGF results in formation of initial FGF-HSPG complexes, which promotes the rapid binding of FGFR and creates a ternary complex capable of undergoing dimerization and subsequent FGFR activation. In contrast, alternative models for the kinetic assembly of a ternary complex in which binary FGF-FGFR or FGFR-HSPG complexes are intermediates do not conform well with the experimental data.