经典的PDZ结构域结合模式是一种较弱的相互作用，解离常数约为数个-数几十μM。在需要结合特异性很高的区域（如神经突触后膜），这种结合模式并不能解释PDZ结构域与目标蛋白结合的高特异性。本课题组在前期工作中发现INAD和TRP的相互作用模式很可能是一种新的PDZ结合模式。因此我们拟采用分子生物学与生物化学的方法，分别表达、纯化和优化INAD与TRP蛋白的相互作用区域，用分析型超速离心技术测定两者相互作用的结合常数，然后以X射线衍射的方法解析INAD/TRP蛋白复合物的晶体结构，最后通过一系列定点突变实验来验证该结构的准确性。通过解析INAD/TRP蛋白复合物结构，本课题组将有望发现一种新的PDZ结合目标蛋白的模式；而这种结合模式，在目前的技术手段下是无法通过传统的大规模筛选得到的。这一预期成果，将为日后筛选新的PDZ结合蛋白提供线索，同时也将为体外重组INAD信号转导复合物的研究打下基础。

The canonical binding mode of PDZ domain is a relative weak interaction. The binding affinity between PDZ domain and its target is about several to tens of μM. In some regions of cell (for example, postsynaptic density), this kind of weak interaction can not explain the high specificity that the PDZ domains required for the interaction with their targets. In our previous study, we found that the interaction mode of INAD/TRP complex may be a novel interaction mode. To test this hypothesis, the binding regions in INAD and TRP protein will be expressed, purified and their boundaries will be optimized. The binding affinity between INAD and TRP will be measured by analytical ultracentrifugation and the INAD/TRP complex structure will be solved by X-ray crystallography method. Finally, point mutations will be used to verify the accuracy of the complex structure. By solving the crystal structure of INAD/TRP complex, we aim to discover a novel binding mode of PDZ/target interaction. And this novel binding mode can not be screened out by traditional phage-display or peptide-array techniques. The discovery of this novel binding mode will provide some clues for screening new PDZ binding targets and also the structural basis for reconstitution of the INAD signal complex in vitro in the future.