Mammalian scribble forms a tight complex with the βPIX exchange factor
Mammalian scribble forms a tight complex with the βPIX exchange factor
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DOI：
10.1016/j.cub.2004.05.051
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发表时间：
2004-06-08
期刊：
影响因子：
9.2
通讯作者：
Borg, JP
中科院分区：
文献类型：
--
作者：
Audebert, S;Navarro, C;Borg, JP
果蝇Scribble与正常突触结构和上皮组织的发育有关，但它如何发挥作用以及它控制哪个过程仍不清楚[1-3]。Scribble的哺乳动物同源物hScrib具有与其苍蝇同源物相似的一级结构和亚细胞定位[4]，但其功能尚不清楚。在这里，我们使用串联质谱仪来鉴定hScrib网络的主要组成部分。我们发现它包括鸟嘌呤核苷酸交换因子βPIX(也称为Cool-1)和它的伴侣GIT1(也称为P95-App1)，GTP酶激活蛋白(GAP)[5-8]。BetaPIX直接与hScrib PDZ结构域结合，hScrib/betaPIX复合体在上皮细胞和神经细胞和组织中得到有效恢复。在小脑颗粒细胞培养中，hScrib和PPIX都部分定位于神经元突触前区。此外，我们发现hScrib需要将BetaPIX锚定在细胞皮质，显性负的BetaPIX或hScrib蛋白都可以抑制神经内分泌PC12细胞中依赖钙的胞吐，证明了这些蛋白之间的功能关系。这些数据揭示了hScrib/betaPIX紧密相互作用的存在，并表明这种复合体可能在神经元传递中发挥作用。
Drosophila Scribble is implicated in the development of normal synapse structure and epithelial tissues, but it remains unclear how it plays a role and which process it controls [1-3]. The mammalian homolog of Scribble, hScrib, has a primary structure and subcellular localization similar to that of its fly homolog [4], but its function remains unknown. Here we have used tandem mass spectrometry to identify major components of the hScrib network. We show that it includes betaPIX (also called Cool-1), a guanine nucleotide exchange factor (GEF), and its partner GIT1 (also called p95-APP1), a GTPase activating protein (GAP) [5-8]. betaPIX directly binds to the hScrib PDZ domains, and the hScrib/betaPIX complex is efficiently recovered in epithelial and neuronal cells and tissues. In cerebellar granule cell cultures, hScrib and PPIX are both partially localized at neuronal presynaptic compartments. Furthermore, we show that hScrib is required to anchor betaPIX at the cell cortex and that dominant-negative betaPIX or hScrib proteins can each inhibit Ca2+-dependent exocytosis in neuroendocrine PC12 cells, demonstrating a functional relationship between these proteins. These data reveal the existence of a tight hScrib/ betaPIX interaction and suggest that this complex potentially plays a role in neuronal transmission.