A interacting protein specific to alpha-1 adrenoceptor modifies the receptor's function

蛋白质间相互作用是受体生物学研究的热点之一。我们推测α-<1A>肾上腺素能受体（α-<1A>AR）与一种相互作用的蛋白质相互作用，调节受体在天然组织中的功能。为了筛选与α-AR相互作用的候选蛋白<1A>，我们以α-AR为诱饵，利用酵母双杂交技术从人脑cDNA文库中筛选出与α-AR相互作用的候选蛋白。因此，Snapin，被称为SNARE复合物的结合配偶体被鉴定。Snapin与PC 12细胞质膜上的α-AR相互作用并共定位<1A>。此外，我们还发现<1A>当Snapin与α-AR共表达时，α-AR激活后的钙离子内流明显增加<1A>。另一方面，Snapin与TRPC 6通道相互作用，TRPC 6通道现在被认为是受体操纵的钙通道之一。α-AR的激活<1A>可诱导受体之间的相互作用，增加TRPC 6向细胞表面的募集。我们的数据提示了一种新的受体操纵的信号传导机制，Snapin将α_<1A>-AR连接到TRPC 6，通过受体操纵的钙通道增加钙内流。

Protein-to-protein interaction is one of the topics in receptor biology. We hypothesized that the α_<1A>-adrenoceptor (α_<1A>-AR) is accompanied with an interacting protein which modulates a receptor's function in native tissues. To isolate candidate proteins interacting with α_<1A>-AR, we searched human brain cDNA library by yeast two-hybrid method using the receptor as bait. As a result, Snapin, known as a binding partner of SNARE complex was identified. Snapin interacts and co-localizes with the α_<1A>-AR on plasma membrane of PC12 cells. Additionally, we found that the calcium entry upon α_<1A>-AR activation was significantly augmented when Snapin was co-expressed with the α_<1A>-AR in PC12 cells. On the other hand, Snapin interacts with TRPC6 channel which is now believed to be one of the receptor-operated calcium channels. Activation of the α_<1A>-AR induced the interaction between the receptor, increasing the recruitment of TRPC6 to the cell surface. Our data suggest a new receptor-operated signaling mechanism, where Snapin links the α_<1A>-AR to TRPC6, augmented calcium influx via receptor-operated calcium channels.