G protein-mediated modulation of synaptic vesicle fusion

突触传递有效性的调制是神经可塑性的关键组成部分，而神经可塑性反过来又是一种 大脑的定义特征。位于突触前终末的受体已知会深深地抑制 神经递质释放。在这些G蛋白偶联受体中，G蛋白偶联受体普遍存在。我们已经证明了 G蛋白偶联受体通过直接在核心复合体介导的作用抑制突触传递 用于囊泡融合。GBG直接与SNAP-25结合，SNAP-25并入启动囊泡的SNARE复合体中。 我们现在假设这种调制的机制是熔融孔隙动力学的变化，因为 突触小泡向突触间隙释放递质。这种传播方式的改变很可能会 对突触传递的实际工作方式和我们的 把它理解为有效的。瞬间融合，在重复活动中保存小泡，它也可能改变 不同亲和力的突触后受体参与突触传递的方式 不同的突触下位置。在这个提案中，我们试图确定突触前的机制 G蛋白偶联受体调节神经递质的释放。我们将量化持续时间 突触前G蛋白使用Striryl引起的突触前终末不完全囊泡融合事件 融合突触小泡的染料标记？我们还希望确定突触前受体的作用 测定和测定突触间隙内神经递质的激活时程和浓度 建立突触后受体激活的动力学模型。我们还将确定改变 这些参数将影响不同突触后亲离子受体的相对激活。最后， 我们将研究突触前G蛋白对个体突触接触特性的影响 高速成像技术。

Modulation of the efficacy of synaptic transmission is a key component of neural plasticity, which is, in turn, a defining feature of the brain. Receptors located on the presynaptic terminal are known to profoundly depress neurotransmitter release. Of these G protein-coupled receptors are ubiquitous. We have demonstrated that G protein-coupled receptors inhibit synaptic transmission by an effect mediated directly at the core complex for vesicle fusion. Gbg binds directly to SNAP-25 incorporated into the SNARE complex of primed vesicles. We now hypothesizethat the mechanism for this modulation is an alteration in fusion pore dynamics as the synaptic vesicle releases transmitter into the synaptic cleft. This change in mode of transmission is likely to have profound consequences both to the way synaptic transmission actually works, and to the way we interpret it as working. Transient fusion, will conserve vesicles during repetitive activity, it may also change the mode of synaptic transmission by favoring different postsynaptic receptors with different affinities and different subsynaptic locations. In this proposal we seek to determine the mechanism by which presynaptic G protein-coupled receptors modulate release of neurotransmitter. We will quantify the duration of incomplete vesicle fusion events from the presynaptic terminal caused by presynaptic G proteins using styryl dye labeling of fusing synaptic vesicles? We also wish to determine the affects of presynaptic receptor activation on the timecourse and concentration of neurotransmitter in the synaptic cleft by measuring and modeling the kinetics of postsynaptic receptor activation. We will also determine the effects that altering these parameters will impose on the relative activation of different postsynaptic ionotropic receptors. Finally, we will investigate the affect of presynaptic G proteins on the properties of individual synaptic contacts using high-speed imaging techniques.