PICK1蛋白C端酸性区域对其功能的调节

蛋白激酶C相互作用蛋白1(protein interacting with Ckinase1,PICK1)是调节AMPA(alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid)受体在细胞膜上的数量与分布,引起LTP与LTD现象的重要蛋白.本文利用基因克隆、荧光光谱以及免疫分析等方法,分析了PICK1蛋白C末端酸性区对BAR结构域与膜脂结合能力以及PICK1分子内BAR(Bin/amphiphysin/RVS)结构域与PDZ结构域相互作用的影响,研究了钙离子结合C末端酸性区后对上述相互作用的调节.结果显示,C末端酸性区的存在使BAR结构域与膜脂的结合能力减弱大约10倍,但PICK1分子内的BAR与PDZ结构域的相互作用与不含C末端的酸性区相比增强了大约4倍.另一方面,C末端酸性区的存在,伴随钙离子浓度的提高,有助于增强BAR与膜脂的结合,却削弱了PDZ和BAR结构域的作用.当钙离子浓度增加到500μmol/L时,BARC的脂质结合能力以及和PDZ的亲和力与不含酸性区相当.

C-terminal Acidic Region Regulates PICK1 Function

The protein interacting with Cα kinase 1 (PICK1) plays an important role in regulating the amount and distribution of AMPA receptors on membrane, which is associated with the LTP or LTD of the synapses. Using gene manipulation combined with fluorescence spectra analyses and ELISA, we have analyzed the interactions of the PICK1 BAR domain with membrane lipids, as well as with the PDZ domain at the C-terminal acidic region of PICK1. The results indicated that the PICK1 C-terminal acidic region reduced the association of the BAR domain and membrane lipids by 10 folds, and increased the association with the BAR domain by 4 folds as compared with that of the PICK1 truncation without the C-terminal acidic region. The Ca2+binding of with the PICK1 C-terminal acidic region enhanced, the binding of BAR with membrane lipids, whereas the interaction of BAR and PDZ was impaired. At an increased Ca2+ level of 500 μmol•L-1, both the binding of BAR to membrane lipids and the affinity to PDZ were reduced and equivalent to those of with the C-terminal region deleted PICK1.