Syntaxin 1A 与 Munc18a 在细胞内的相互作用和定位研究

Syntaxin 1A (Syn1A) 和 Munc18a 蛋白在囊泡转运和分泌中起着至关重要的作用，然而它们在细胞中分选和转运的分子机制目前尚不清楚 . 我们用绿色荧光蛋白 (EGFP) 和红色荧光蛋白 (TDimer2) 分别标记 Syn1A 和 Munc18a ，并用荧光显微技术观察它们在 BHK-21 和 HEK293 细胞中的转运和定位 . 实验结果表明 Syn1A 主要定位在细胞质膜上，而 Munc18a 主要分布在胞浆中，但是与 Syn1A 共表达时能定位到细胞质膜上 . 删除胞浆部分的 Syn1A 蛋白不能上膜，提示其胞浆结构域在分选和定位过程中起着重要的作用 .

Direct Interaction With Syntaxin 1A Defines The Intracellular Localization of Munc18a

Syntaxin 1A (Syn1A) and Munc18a play essential roles in vesicular trafficking and exocytosis. The molecular mechanism underlying the sorting of these two proteins to their physiological sites of action remains poorly understood. Here the localization of syntaxin1A (Syn1A) and Munc18a was analyzed in baby hamster kidney (BHK-21) cells and human embryonic kidney (HEK293) cells. The rat Syn1A gene was fused to the gene encoding the enhanced green fluorescent protein (EGFP). Munc18a was labeled with the red fluorescence protein (TDimer2) at its C terminal. The proteins were expressed by transient transfection in either BHK-21 or HEK293 cells. Under fluorescence microscopy, it was shown that Syn1A was shown to be transported to the plasma membrane. While Munc18a exhibited mainly cytosolic distribution when expressed alone. However, upon coexpression with Syn1A, Munc18a is translocated to the plasma membrane. In addition, a N-terminal truncated mutant Syn1A failed to localize at the plasma membrane, suggesting that the cytoplasmic domain of Syn1A is important for its sorting and localization.