Understanding How Integral Membrane Proteins Influence the Continuum Mechanics of Cell Membranes.

这项建议的目标是建立实验技术并开发基础实验数据，描述一般完整的膜蛋白如何影响生物膜的机械性能。这些工具和结果将对我们理解生物膜作为连续介质材料产生革命性的影响。目前对双层-蛋白质相互作用的研究大多集中在特定蛋白质(SNARE复合体、病毒融合蛋白)如何作用于脂双层，或者脂双层中的力如何调节完整的膜蛋白功能。PI将膜视为一种连续体材料，其中的机械性能由脂类和完整的膜蛋白共同决定。鉴于膜中蛋白质的浓度很高，为了充分了解生物膜如何运动和变形，这样的观点是必要的。膜变形是生物学中的一种中心现象，在细胞分裂、病毒感染和神经递质释放等过程中起着重要作用。这项提案包括一项面向高中生的全面教育计划。这一外展计划的主要目标是促进来自洛杉矶联合学区不同人群的学生获得密集的研究体验。这将通过与旧金山布拉沃医学磁铁高中健康工程学院的一个既定外展项目合作来实现，该项目将把12年级的学生带到实验室进行为期一年的实习。实习生将由该奖项资助的研究生指导，并将进行他们自己的小型独立研究项目。PI将使用标准方法测量巨大单层脂泡(GUV)中的脂双层的机械性质。这项研究的关键创新方面是PI的实验室最近开发的一项技术，该技术可以在相对较高的浓度下将完整的膜蛋白整合到GUV中。这将允许PI检查具有受控浓度的膜蛋白的GUV的机械性能。PI将研究具有各种跨膜基序的蛋白质，以发现跨膜域的结构如何影响蛋白质与双层的机械耦合。将在一定浓度范围内测量每种蛋白质的两种性质：1)薄膜在没有外力的情况下发生弯曲的趋势。这由自发(或本征)曲率JSB来描述。2.)使薄膜偏离其固有曲率弯曲所需的能量。这是由弯曲模数Kc描述的。这两个参数是描述生物过程中膜变形的能量学的中心。PI将使用微吸管吸入和囊泡波动分析的组合来独立确定给定条件下每个参数的值。该项目由物理部的生命系统物理学计划和分子和细胞生物科学部的分子生物物理学计划联合支持。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The goal of this proposal is to establish experimental techniques and develop foundational experimental data describing how general integral membrane proteins affect the mechanical properties of biomembranes. These tools and results will have a transformative effect on our understanding of biomembranes as continuum materials. Most contemporary research in bilayer-protein interactions focuses either on how specific proteins (SNARE complexes, viral fusion proteins) exert force on lipid bilayers or how forces in the lipid bilayer can modulate integral membrane protein function. The PI is looking at the membrane as a continuum material in which the mechanical properties are determined by both the lipids and the integral membrane proteins. Given the high concentration of proteins in the membrane, such a view is necessary in order to fully understand how biomembranes move and deform. Membrane deformation is a central phenomenon in biology, underlying such processes as cell division, viral infection, and neurotransmitter release. This proposal includes a comprehensive educational plan for outreach to high school students. The primary objective of this outreach program is to facilitate intensive research experiences for students drawn from the diverse population of the Los Angeles Unified School District. This will be accomplished by cooperating with an established outreach program at the Engineering for Health Academy at Francisco Bravo Medical Magnet High School to bring grade-12 students into the laboratory for yearlong internships. Interns will be mentored by the graduate student funded by this award and will undertake their own small, independent research projects.The PI will use standard methods for measuring the mechanical properties of lipid bilayers in giant unilamellar lipid vesicles (GUVs). The key innovative aspect of this research is enabled by a technology that the PI's laboratory recently developed to incorporate integral membrane proteins into GUVs at relatively high concentrations. This will allow the PI to examine the mechanical properties on GUVs with controlled concentrations of membrane proteins. The PI will investigate proteins with a variety of transmembrane motifs to discover how the structure of the transmembrane domains affects how proteins are mechanically coupled to the bilayer. The two properties that will be measured for each protein at a range of concentrations are: 1.) The tendency of a membrane to bend when no external forces are applied. This is described by the spontaneous (or intrinsic) curvature JSB. 2.) The amount of energy required to bend the membrane away from its intrinsic curvature. This is described by the bending modulus kc. These two parameters are central to describing the energetics of membrane deformation during biological processes. The PI will use a combination of micropipette aspiration and vesicle fluctuation analysis to independently determine the value of each parameter for a given set of conditions.This project is being jointly supported by the Physics of Living Systems program in the Division of Physics and the Molecular Biophysics program in the Division of Molecular and Cellular Biosciences.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.