Tsujimoto S, Bean A J
Department of Neurobiology, W.M. Keck Center for the Neurobiology of Learning and Memory, Houston, Texas 77030, USA.
J Biol Chem. 2000 Jan 28;275(4):2938-42. doi: 10.1074/jbc.275.4.2938.
Regulated secretion of neurotransmitter at the synapse is likely to be mediated by dynamic protein interactions involving components of the vesicle (vesicle-associated membrane protein; VAMP) and plasma membrane (syntaxin and synaptosomal associated protein of 25 kDa (SNAP-25)) along with additional molecules that allow for the regulation of this process. Recombinant Hrs-2 interacts with SNAP-25 in a calcium-dependent manner (they dissociate at elevated calcium levels) and inhibits neurotransmitter release. Thus, Hrs-2 has been hypothesized to serve a negative regulatory role in secretion through its interaction with SNAP-25. In this report, we show that Hrs-2 and SNAP-25 interact directly through specific coiled-coil domains in each protein. The presence of syntaxin enhances the binding of Hrs-2 to SNAP-25. Moreover, while both Hrs-2 and VAMP can separately bind to SNAP-25, they cannot bind simultaneously. Additionally, the presence of Hrs-2 reduces the incorporation of VAMP into the syntaxin.SNAP-25.VAMP (7 S) complex. These findings suggest that Hrs-2 may modulate exocytosis by regulating the assembly of a protein complex implicated in membrane fusion.
突触处神经递质的调节性分泌可能是由动态蛋白质相互作用介导的，这些相互作用涉及囊泡成分（囊泡相关膜蛋白；VAMP）和质膜成分（ syntaxin和25 kDa的突触体相关蛋白（SNAP-25））以及其他可调节此过程的分子。重组Hrs-2以钙依赖的方式与SNAP-25相互作用（它们在钙水平升高时解离）并抑制神经递质释放。因此，有人推测Hrs-2通过与SNAP-25相互作用在分泌中起负调节作用。在本报告中，我们表明Hrs-2和SNAP-25通过每种蛋白质中的特定卷曲螺旋结构域直接相互作用。 syntaxin的存在增强了Hrs-2与SNAP-25的结合。此外，虽然Hrs-2和VAMP都可以分别与SNAP-25结合，但它们不能同时结合。此外，Hrs-2的存在减少了VAMP掺入syntaxin.SNAP-25.VAMP（7S）复合物中。这些发现表明，Hrs-2可能通过调节参与膜融合的蛋白质复合物的组装来调节胞吐作用。
