Ion channel regulation by heterogeneous membranes

离子通道是一种膜结合蛋白，通过选择性地控制 带电离子通过膜的流动。大多数频道都嵌入了复杂的成分中 神经细胞膜，其详细的组成在调节通道功能中起着重要作用。 膜可以通过将特定的成分结合到通道内的位置来直接调节通道 结构，或间接地通过影响生物物理和生化过程来调节通道 在它们的原生环境中发挥作用。膜成分影响的机械论理解 通道功能至关重要，因为神经细胞膜成分的变化与正常 发育和神经疾病。拟议研究的目标是测试三种不同的机制。 组成复杂的膜通过这些膜调节通道功能。工作假说， 由PL和COL过去的协作工作支持的是，一些渠道职能由 由于这些膜是非均相的，它们的嵌入膜的紧急性质。 在广泛的初步数据的指导下，我们将追求三个具体目标：1)测量功能耦合 通道状态对膜结构域的影响，2)确定膜结构域如何影响变构结合 监管机构，以及3)确定膜结构域在更广泛的监管环境中的作用 神经元。第一个目标是通过实验测试一个最小模型，该模型假定单通道函数是 通过调节首选药物的利用度来调节包埋膜内结构域对变构的调节 局部脂质环境。第二个目标是探索已知的变构调节剂的化学势 如胆固醇和肌醇磷脂受相同的热力学参数的影响 控制膜结构域的属性。第三个目标是研究膜结构域如何影响 参与蛋白质棕榈酰化和酪氨酸磷酸化调节通路的酶的分类 发生在神经元突触处。实验方法利用PIS的专业知识，使用定量超分辨率 荧光定位显微镜技术，并与功能研究，理论， 和模拟，以测试和提炼孤立和集体渠道功能的机制模型。这个 所提出的工作具有创新性，因为它将膜组织的预测模型应用于 通道和膜域群落。一个广泛适用的框架，用于描述 调节通道功能的领域将通过提供对 随着发育和神经系统疾病的发生，膜的功能基础发生变化，会激发更多的动力 对神经系统疾病的有效和有针对性的治疗，并将连接分子尺度的行为 通过脂质和膜域的集体作用，引导神经科学中更大的问题。

Ion channels are membrane bound proteins that mediate fast neural dynamics by selectively controlling the flow of charged ions across membranes. Most channels are embedded within compositionally complex neuronal membranes, whose detailed composition play important roles in regulating channel functions. Membranes can regulate channels directly, through the binding of specific components to sites within channel structures, or indirectly, by impacting the biophysical and biochemical processes evolved to regulate channel functions in their native environment. A mechanistic understanding of how membrane composition impacts channel functions is vital because changes in neuronal membrane composition are associated with normal development and neurological disease. The goal of the proposed studies is to test three distinct mechanisms through which compositionally complex membranes regulate channel function. The working hypothesis, supported by past collaborative work of the Pl and Col, is that some channel functions are regulated by emergent properties of their embedding membranes that occur because these membranes are heterogeneous. Guided by extensive preliminary data, three specific aims will be pursued: 1) Measure the functional coupling of channel states to membrane domains, 2) Establish how membrane domains impact the binding of allosteric regulators, and 3) Identify the roles of membrane domains within the broader regulatory environment of neurons. The first aim experimentally tests a minimal model positing that single channel functions are allosterically regulated by domains within embedding membranes through tuning the availability of preferred local lipid environments. The second aim explores how the chemical potential of known allosteric regulators such as cholesterol and phosphoinositide lipids are impacted by the same thermodynamic parameters that control properties of membrane domains. The third aim investigates how membrane domains impact the sorting of enzymes that participate in protein palmitoylation and tyrosine phosphorylation regulatory pathways occurring at neuronal synapses. Experimental approaches draw on the PIs expertise using quantitative super-resolution fluorescence localization microscopy techniques and are combined with functional studies, theory, and simulation to test and refine mechanistic models of isolated and collective channel functions. The proposed work is innovative because it applies predictive models of membrane organization that are novel to both the channel and membrane domain communities. A broadly applicable framework for describing how domains modulate channel functions will drive advances in neuroscience by providing new insights into the functional basis for membrane changes with development and neurological disease, will motivate more effective and targeted treatments for neurological disease, and will connect the molecular-scale behaviors of channels to larger questions in neuroscience through the collective actions of lipids and membrane domains.