突触结合蛋白Ⅰ的胞质片段与磷脂膜的相互作用  

Interaction of Cytoplasmic Part of SynaptotagminⅠwith Phospholipid Membrane

作　　者：贺雨虹[1] 隋森芳[1] 

机构地区：[1]清华大学生物科学与技术系

出　　处：《生物化学与生物物理进展》2003年第1期84-88,共5页Progress In Biochemistry and Biophysics

基　　金：国家自然科学基金资助项目 ( 30 170 16 9) .

摘　　要：突触结合蛋白Ⅰ是神经细胞突触囊泡上的一个膜整合蛋白 ,C2AB是其具有重要功能的胞质片段 .近年的研究表明 ,突触结合蛋白Ⅰ在钙引发的神经递质快速释放过程中起到钙感受器的作用 ,它与神经细胞突触前膜的相互作用与其生理功能有关 ,但是其作用机制还不清楚 .利用气 /液单层膜技术结合荧光发射光谱和圆二色光谱技术 ,发现C2AB倾向于插入带负电荷的磷脂膜中 (如磷脂酰丝氨酸 ) ,而且插膜是钙依赖性的 ;对于不带电荷的磷脂不插膜 .C2AB与膜之间的作用力主要为静电力 .荧光发射光谱和圆二色光谱结果显示 ,它与膜相互作用时二级结构不发生显著变化 .结果表明 ,突触结合蛋白Ⅰ钙依赖的插入负电荷膜特点 ,可以帮助解释其钙感受器的作用机制 .SynaptotagminⅠ(sytⅠ) is an abundant integral membrane protein of synaptic vesicle and the C2AB domain is the important functional domain in its cytoplasmic part. Recent studies show that C2AB prefers to interact with plasmic membranes of neuron cells in vivo and it is believed that such interaction is closely related to the sytⅠ physiological function as a Ca 2+ sensor in the Ca 2+ - regulated neurotransmitter release, but the mechanism of the interaction is not clearly understood. Monolayers at an air/water interface combined CD and fluorescence experiments were used to study the characteristic of interaction between C2AB and a phospholipid membrane. The results in the monolayer experiment showed that C2AB domain preferred insertion into the negatively charged phosphatidylserine monolayer and Ca 2+ ions were required for the interaction. Electrostatic force was mostly responsible for the insertion of C2AB into PS monolayers. Further CD and fluorescence experiments showed that the secondary structure of C2AB domain in the presence or absence of PS/PC liposome had some relatively small change. The experiments provide useful information concerning the important role of sytⅠ as a Ca 2+ sensor in the fusion of secretary vesicles to the plasma membrane, and better understanding the mechanisms of membrane fusion in exocytosis.

关 键 词：突触结合蛋白I 胞质片段 磷脂膜 相互作用 临界插膜压 神经细胞 

分 类 号：Q593.2[生物学—生物化学] Q421