| Polyamine Transport Assay Using Reconstituted Yeast Membranes
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Author:
Date:
2021-01-20
[Abstract] ATP13A2/PARK9 is a late endo-/lysosomal P5B transport ATPase that is associated with several neurodegenerative disorders. We recently characterized ATP13A2 as a lysosomal polyamine exporter, which sheds light on the molecular identity of the unknown mammalian polyamine transport system. Here, we describe step by step a protocol to measure radiolabeled polyamine transport in reconstituted vesicles from yeast cells overexpressing human ATP13A2. This protocol was developed as part of our recent publication (van Veen et al., 2020) and will be useful for characterizing the transport function of other putative polyamine transporters, such as isoforms of the P5B transport ATPases.
[摘要] [摘要] ATP13A2 / PARK9是一种晚期内/溶酶体P5B转运ATPase，与多种神经退行性疾病有关。我们最近将ATP13A2表征为溶酶体多胺出口者，这为未知的哺乳动物多胺转运系统的分子身份提供了线索。在这里，我们逐步描述了从过量表达人ATP13A2的酵母细胞中测量重组囊泡中放射性标记的多胺转运的方案。该方案是我们最新出版物的一部分（van Veen等，2020），将有助于表征其他假定的多胺转运蛋白的转运功能，例如P5B转运ATPase的同工型。
[背景] ATP13A2 / PARK9编码一种普遍表达的晚期内-/溶酶体膜蛋白，与一系列神经退行性疾病有关，例如早发性帕金森氏病（Di Fonzo等，2007 ；Lin等，2008）和Kufor -Rakeb综合征（伴痴呆的早期帕金森病）（Ramirez等，2006 ；Park等，2011）。ATP13A2属于P型转运ATPase ，是一类活性转运蛋白，由于ATP水解而暂时形成磷酸中间产物（Kuhlbrandt ，2004年）。ATP13A2是P5亚家族的成员，该家族已在20多年前通过基因组测序鉴定出来（Axelsen和Palmgren ...
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| Expression and Purification of a Mammalian P2X7 Receptor from Sf9 Insect Cells
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Author:
Date:
2017-09-05
[Abstract] The P2X7 receptor is an extracellular ATP-gated ion channel found only in eukaryotes (Bartlett et al., 2014). Due to its unique properties among P2X receptors, such as formation of a large conductance pore, the P2X7 receptor has been implicated in devastating diseases like chronic pain (North and Jarvis, 2013). However, mechanisms underlying the P2X7 specific properties remain poorly understood, partly because purification of this eukaryotic membrane protein has been challenging. Here we describe a detailed protocol for expressing and purifying a mammalian P2X7 receptor using an insect cell-baculovirus system. The P2X7 receptor is expressed in Sf9 insect cells as a GFP fusion protein and solubilized with a buffer containing Triton X-100 detergent. The P2X7-GFP fusion protein is ...
[摘要] P2X7受体是仅在真核生物中发现的胞外ATP门控离子通道（Bartlett等，2014）。由于其P2X受体之间的独特性质，例如大电导孔的形成，P2X7受体已经涉及破坏性疾病如慢性疼痛（North和Jarvis，2013）。然而，P2X7特异性属性的机制仍然知之甚少，部分原因是纯化这种真核膜蛋白是一个挑战。在这里，我们描述了使用昆虫细胞 - 杆状病毒系统表达和纯化哺乳动物P2X7受体的详细方案。 P2X7受体在作为GFP融合蛋白的Sf9昆虫细胞中表达，并用含有Triton X-100洗涤剂的缓冲液溶解。然后使用Strep-Tactin亲和层析在含有十二烷基麦芽糖苷的缓冲液中纯化P2X7-GFP融合蛋白。在通过凝血酶酶切割连接的GFP和Strep-标签后，使用大小排阻色谱分离P2X7受体。该方法通常从6L的Sf9培养物产生约2mg的纯化蛋白质。纯化的蛋白质可以用含有15％甘油的缓冲液在4℃下储存至少2个月，并用于各种功能和结构研究（Karasawa和Kawate，2016）。
【背景】P2X7受体是嘌呤能P2X受体家族的七种亚型之一，并且是广泛疾病如神经退行性疾病，癫痫和神经性疼痛的有希望的新型药物靶点（North和Jarvis，2013; Bhattacharya和Biber， ...
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| Fluorophore Labeling, Nanodisc Reconstitution and Single-molecule Observation of a G Protein-coupled Receptor
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Author:
Date:
2017-06-20
[Abstract] Activation of G protein-coupled receptors (GPCRs) by agonist ligands is mediated by a transition from an inactive to active receptor conformation. We describe a novel single-molecule assay that monitors activation-linked conformational transitions in individual GPCR molecules in real-time. The receptor is site-specifically labeled with a Cy3 fluorescence probe at the end of trans-membrane helix 6 and reconstituted in phospholipid nanodiscs tethered to a microscope slide. Individual receptor molecules are then monitored over time by single-molecule total internal reflection fluorescence microscopy, revealing spontaneous transitions between inactive and active-like conformations. The assay provides information on the equilibrium distribution of inactive and active receptor conformations and ...
[摘要] 通过激动剂配体激活G蛋白偶联受体（GPCR）是通过从无活性受体构象向活性受体构象的转变来介导的。我们描述了一种新颖的单分子测定法，可以实时监测单个GPCR分子中的激活连锁构象转换。受体在跨膜螺旋6末端用Cy3荧光探针进行位点特异性标记，并在连接到显微镜载玻片的磷脂纳米圆盘中重构。然后通过单分子全内反射荧光显微镜随时间监测单个受体分子，显示无活性和活性样构象之间的自发转变。该测定提供关于无活性和活性受体构象的平衡分布以及构象交换的速率常数的信息。实验可以在不存在配体的情况下进行，显示负责基础信号传导活动的自发构象过渡，或者存在激动剂或反向激动剂配体，揭示配体如何改变受体的动力学刺激或抑制信号传导活性。所得到的机械信息对于改进的GPCR靶向药物的设计是有用的。单分子测定法在β2肾上腺素能受体的背景下进行了描述，但可扩展到多种GPCRs。
【背景】GPCR介导本地和远距离的细胞通讯，特别是内分泌系统。例如，细胞对激素如肾上腺素的反应是通过肾上腺素能受体介导的，其中β2肾上腺素能受体（β2AR）是突出的成员。 ...
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