Exocyst complex subunit sec8 binds to postsynaptic density protein-95 (PSD-95): a novel interaction regulated by cypin (cytosolic PSD-95 interactor)
Exocyst complex subunit sec8 binds to postsynaptic density protein-95 (PSD-95): a novel interaction regulated by cypin (cytosolic PSD-95 interactor)
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DOI：
10.1042/bj20021838
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发表时间：
2003-07-01
影响因子：
4.1
通讯作者：
Firestein, BL
中科院分区：
文献类型：
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作者：
Riefler, GM;Balasingam, G;Firestein, BL
突触后致密蛋白（PSD）95的PDZ结构域在PSD-95和结合伴侣定位于神经元突触中发挥作用。识别这些PDZ结构域的结合伴侣可以帮助我们了解信号复合物是如何组装的。我们观察到sec6/8或外囊复合物中的一个亚基sec8含有用于PDZ结合的C-末端共有序列。Sec8与PSD-95的PDZ 1 - 2结合，并且这种结合可以与在肽结合位点与PDZ 1和PDZ 2结合的肽竞争。此外，sec8的结合依赖于其C-末端结合序列，即Thr-Thr-瓦尔（TTV）。大鼠组织提取物的免疫印迹显示，sec8和PSD-95富集在相同的脑区域，sec8和PSD-95在嗜铬细胞瘤细胞中具有相同的亚细胞分布，这表明这些蛋白质可能在体内相互作用。脑中sec8和PSD-95的免疫沉淀研究提供了sec8和PSD-95相互作用的进一步证据。此外，胞质PSD-95相互作用物与sec8竞争与PSD-95的相互作用。两者合计，我们的研究结果表明，胞质PSD-95相互作用可能起到调节sec8的能力，结合PSD-95。
The PDZ domains of postsynaptic density (PSD) protein-95 play a role in the localization of PSD-95 and binding partners to neuronal synapses. The identification of binding partners to these PDZ domains can help us in understanding how signalling complexes are assembled. We observed that one of the subunits in the sec6/8 or exocyst complex, sec8, contains a C-terminal consensus sequence for PDZ binding. Sec8 binds to PDZ1-2 of PSD-95, and this binding can be competed with a peptide that binds to PDZ1 and PDZ2 in the peptide-binding site. In addition, binding of sec8 is dependent on its C-terminal-binding sequence namely Thr-Thr-Val (TTV). Immunoblotting of rat tissue extracts shows that sec8 and PSD-95 are enriched in the same brain regions, and sec8 and PSD-95 have the same subcellular distribution in pheochromocytoma cells, suggesting that these proteins may interact in vivo. Immunoprecipitation studies of sec8 and PSD-95 in brain provide further evidence of a sec8 and PSD-95 interaction. Furthermore, the cytosolic PSD-95 interactor competes with sec8 for interaction with PSD-95. Taken together, our results suggest that the cytosolic PSD-95 interactor may function to regulate the ability of sec8 to bind to PSD-95.