我们感谢阮阅读的手稿和一般实验室援助第六。

1。 农杆菌文化的制备<ol><li> 农杆菌菌株GV3101中转换网关兼容附设载体pEarleyGate201 YC和pEarleyGate202 - YN，每个包含一个融合构建印尼政府。 </li><li>接种5毫升YEB（5G L - 1牛肉膏，1G L - 1酵母提取物，5G L - 1的蛋白胨，5G L - 1蔗糖，硫酸镁2MM 4，pH值7.2）附设的融合蛋白文化建设与农杆菌转化选择适当的抗生素。成长培养过夜，在28 ° C晃动在200转。 </li><li>进入无菌1.5 mL离心管中取出1毫升文化。 </li><li>在1000克颗粒细胞在室温为10分钟，弃上清。 </li><li>通过加入1毫升的渗透媒体（5克L - 1 D -葡萄糖，50毫米MES（Sigma公司），2毫米的Na 3 PO 4，0.1毫米乙酰丁香酮）11的洗涤沉淀。吹打悬浮颗粒，颗粒细胞，在1000克10分钟。 </li><li>重复洗涤步骤两次。 </li><li>重悬在0.5毫升渗透媒体的沉淀。 </li><li>在600 nm测量吸光度和调整的最后600外径为1.0至1.2。 </li><li>到一个新的1.5 ml管分装一个等量的农杆菌悬浮每个构造，持续10秒的旋涡。对于一个单一的渗透，100μL每个构造是绰绰有余。 </li><li> 农杆菌混合物渗透。 </li></ol> 2。浸润<ol start="11"><li> 本生烟的植物生长在21 ° C，16 h光照8小时黑暗周期。 5至6周老厂，应使用渗透。 </li><li> infiltratring让气孔完全开放之前，应删除的增长空间和1小时的白光下的植物。 </li><li>绘制在1毫升滑尖结核菌素注射器无针悬浮农杆菌介导的混合物。 </li><li>将注射器对叶底面的提示，同时直接支持的上部叶用一个手指轻轻压下柱塞。液体会漫过的叶子，因为它填补了mesophyllar的空气空间。 </li><li>为将来识别标签记号笔渗透的领域。 </li><li>与不同的结构渗透时，一定要改变你的手套或清洁与70％之间的渗透乙醇。如果可能的话，不同样品之间留下一脉的空间，以防止交叉污染。 </li><li>增长柜放置在正常生长条件下的植物。 </li></ol> 3。观察重组YFP的信号<ol start="18"><li>海关采用5mm x 5mm的部分叶组织内的渗透区</li><li>装入样品，水，玻璃显微镜玻片上，盖上盖玻片样品，并用共聚焦荧光显微镜检查的相互作用。 </li><li>表达应渗透时间长达5天后每24小时监测，可能会导致过度表达/贩卖超过一个时间过程的几个不同的位置显示在荧光融合蛋白质。 </li></ol> 4。代表性的成果: 附设实验测试的蛋白质相互作用的一个例子是如图1所示。 AtTHP1和AtSAC3A被认为是拟南芥同源酵母TREX - 2复杂的组成部分。他们可以与一个nuclearporin AtNUP1和促进mRNA的出口10。 AtTHP1和AtSAC3A分别克隆到pEarlyGate201 - YC而AtNUP1 pEarlyGate202 - YN克隆。随后被转化为GV3101中的构造。三个结构有3种可能的组合渗透（AtTHP1 + AtNUP1; AtNUP1 AtSAC3A; AtTHP1 + AtSAC3A）配对。下一个LCSM浸润后48小时观察重组YFP的信号。在表皮细胞中观察到的信号，并在核周边或核浆，这是符合这些蛋白质的亚细胞定位的本地化。阴性对照组没有表现出任何YFP的信号。 <img src="/files/ftp_upload/3473/3473fig1.jpg" alt="图1" /> 图1。 拟南芥了TREX - 2 mRNA的出口复杂的组件彼此互动。N。 benthamiana叶，与印度政府结构合作转化融合pEarleyGate201 YC和pEarleyGate202 - YN（表示），成像渗透后48-72 h，采用了Leica TCS SP2共聚焦显微镜。图片显示为合并后的焦YFP的表皮 N.亮场图像benthamiana叶细胞

<ol>
	<li>Ohad, N., Yalovsky, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Utilizing+bimolecular+fluorescence+complementation+(BiFC)+to+assay+protein-protein+interaction+in+plants.">Utilizing bimolecular fluorescence complementation (BiFC) to assay protein-protein interaction in plants.</a> Methods in molecular biology. 655, 347-358 (2010).</li><li>Fang, Y., Spector, D. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=BiFC+imaging+assay+for+plant+protein-protein+interactions.">BiFC imaging assay for plant protein-protein interactions.</a> Cold Spring Harbor protocols. 2, (2010).</li><li>Schutze, K., Harter, K., Chaban, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bimolecular+fluorescence+complementation+(BiFC)+to+study+protein-protein+interactions+in+living+plant+cells.">Bimolecular fluorescence complementation (BiFC) to study protein-protein interactions in living plant cells.</a> Methods in molecular biology. 479, 189-202 (2009).</li><li>Hiatt, S. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bimolecular+fluorescence+complementation+(BiFC)+analysis+of+protein+interactions+in+Caenorhabditis+elegans.">Bimolecular fluorescence complementation (BiFC) analysis of protein interactions in Caenorhabditis elegans.</a> Methods. 45, 185-191 (2008).</li><li>Barnard, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+and+implementation+of+split-GFP-based+bimolecular+fluorescence+complementation+(BiFC)+assays+in+yeast.">Development and implementation of split-GFP-based bimolecular fluorescence complementation (BiFC) assays in yeast.</a> Biochemical Society Transactions. 36, 479-482 (2008).</li><li>Kerppola, T. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Design+and+implementation+of+bimolecular+fluorescence+complementation+(BiFC)+assays+for+the+visualization+of+protein+interactions+in+living+cells.">Design and implementation of bimolecular fluorescence complementation (BiFC) assays for the visualization of protein interactions in living cells.</a> Nature. 1, 1278-1286 (2006).</li><li>Hu, C. D., Grinberg, A. V., Kerppola, T. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Visualization+of+protein+interactions+in+living+cells+using+bimolecular+fluorescence+complementation+(BiFC)+analysis.">Visualization of protein interactions in living cells using bimolecular fluorescence complementation (BiFC) analysis.</a> Current protocols in cell biology. 21, 3-3 (2006).</li><li>Earley, K. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gateway-compatible+vectors+for+plant+functional+genomics+and+proteomics.">Gateway-compatible vectors for plant functional genomics and proteomics.</a> The Plant journal : for cell and molecular biology. 45, 616-629 (2006).</li><li>Karimi, M., Inze, D., Depicker, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=GATEWAY+vectors+for+Agrobacterium-mediated+plant+transformation.">GATEWAY vectors for Agrobacterium-mediated plant transformation.</a> Trends in Plant Science. 7, 193-195 (2002).</li><li>Lu, Q. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Arabidopsis+homolog+of+the+yeast+TREX-2+mRNA+export+complex:+components+and+anchoring+nucleoporin.">Arabidopsis homolog of the yeast TREX-2 mRNA export complex: components and anchoring nucleoporin.</a> The Plant journal : for cell and molecular biology. 61, 259-270 (2010).</li><li>Sparkes, I. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=transient+expression+of+fluorescent+fusion+proteins+in+tobacco+plants+and+generation+of+stably+transformed+plants.">transient expression of fluorescent fusion proteins in tobacco plants and generation of stably transformed plants.</a> Nature protocols. 1, 2019-2025 (2006).</li><li>Rackham, O., Brown, C. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Visualization+of+RNA-protein+interactions+in+living+cells:+FMRP+and+IMP1+interact+on+mRNAs.">Visualization of RNA-protein interactions in living cells: FMRP and IMP1 interact on mRNAs.</a> The EMBO journal. 23, 3346-3355 (2004).</li><li>Demidov, V. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fast+complementation+of+split+fluorescent+protein+triggered+by+DNA+hybridization.">Fast complementation of split fluorescent protein triggered by DNA hybridization.</a> Proceedings of the National Academy of Sciences of the United States of America. 103, 2052-2056 (2006).</li><li>Shyu, Y. J., Suarez, C. D., Hu, C. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Visualization+of+ternary+complexes+in+living+cells+by+using+a+BiFC-based+FRET+assay.">Visualization of ternary complexes in living cells by using a BiFC-based FRET assay.</a> Nature. 3, 1693-1702 (2008).</li></ol>

没有利益冲突的声明。

附设实验是研究蛋白质相互作用的有力工具。附设不同于传统的Y2H检测，不仅可以使蛋白质 - 蛋白质相互作用的可视化，而且还提供了更多的蛋白质复合体的亚细胞定位等信息。此外，它是可能的，只要检测到间接的相互作用的两个候选蛋白可以由第三方的合作伙伴带来足够接近。任何技术一样，附设有其局限性。由于附设的荧光基团形成的氧分子的要求，不能用于专性厌氧菌，在氧气存在的无?...

<table border='1'>
	<tbody>
		<tr>
			<td>Name of the reagent</td>
			<td>Company</td>
			<td>Catalogue number</td>
		</tr>
		<tr>
			<td>Acetosyringone</td>
			<td>Sigma</td>
			<td>D134406</td>
		</tr>
		<tr>
			<td>MES hydrate</td>
			<td>Sigma</td>
			<td>M2933</td>
		</tr>
		<tr>
			<td>1 mL slip-tip tuberculin syringe</td>
			<td>BD</td>
			<td>309602</td>
		</tr>
	</tbody>
</table>

detection of protein interactions in plant using a gateway compatible bimolecular fluorescence complementation (bifc) system

我们已经开发出一种附设的技术测试体内的蛋白质之间的相互作用。这是通过一个黄色荧光蛋白（YFP）分裂成两个非重叠的片段。每帧到一个感兴趣的基因片段克隆。然后，这些结构可以合作转化为烟草通过农杆菌介导的转化，使过境融合蛋白表达。重组YFP的信号只发生时，研讯的蛋白质相互作用1-7。测试和验证的蛋白质 - 蛋白质相互作用，附设可以一起使用的酵母双杂交（Y2H）检测。这可能会侦测到间接的相互作用，可在Y2H忽视。 Gateway技术是一个通用平台，使研究人员感兴趣的基因（GOI）穿梭成尽可能多的表达和功能分析系统， 可能 8,9 。可维持的方向和阅读框，而无需使用限制性内切酶或结扎表达准备克隆。因此，可以消除所有的重测序步骤，以确保在整个实验一致的结果。我们已经建立了一系列网关兼容附设和Y2H载体，提供易于使用的工具执行附设的Y2H检测的研究人员10。在这里，我们展示了易于使用我们的附设系统测试N中的蛋白质-蛋白质相互作用benthamiana植物。

Watch this Scientific Journal Video about Detection of Protein Interactions in Plant using a Gateway Compatible Bimolecular Fluorescence Complementation BiFC System at JoVE.com

Detection of Protein Interactions in Plant using a Gateway Compatible Bimolecular Fluorescence Complementation BiFC System

我们已经开发出一种技术，以测试植物蛋白质相互作用。一个黄色荧光蛋白（YFP）被分成两个非重叠的片段。每个帧通过网关系统的兴趣基因片段克隆，使融合蛋白的表达。重组YFP的信号只发生在研讯的蛋白质相互作用。

使用网关兼容双分子荧光互补（附设）系统在植物蛋白相互作用检测

We have developed a BiFC technique to test the interaction between two proteins in vivo. This is accomplished by splitting a yellow fluorescent protein ...

detection-protein-interactions-plant-using-gateway-compatible

Universidad de Cartagena UDEC

Research

JoVE Journal

Biology

Detection of Protein Interactions in Plant using a Gateway Compatible Bimolecular Fluorescence Complementation (BiFC) System

25.2K 次观看.  University of Western Ontario. 我们已经开发出一种技术，以测试植物蛋白质相互作用。一个黄色荧光蛋白（YFP）被分成两个非重叠的片段。每个帧通过网关系统的兴趣基因片段克隆，使融合蛋白的表达。重组YFP的信号只发生在研讯的蛋白质相互作用。

视频: Detection of Protein Interactions in Plant using a Gateway Compatible Bimolecular Fluorescence Complementation BiFC System

Using the GELFREE 8100 Fractionation System for Molecular Weight-Based Fractionation with Liquid Phase Recovery

The GELFREE 8100 Fractionation System is a novel protein fractionation system designed to maximize protein recovery during molecular weight based fractionation. The system is comprised of single-use, 8-sample capacity cartridges and a benchtop GELFREE Fractionation Instrument. During separation, a constant voltage is applied between the anode and cathode reservoirs, and each protein mixture is electrophoretically driven from a loading chamber into a specially designed gel column gel. Proteins are concentrated into a tight band in a stacking gel, and separated based on their respective electrophoretic mobilities in a resolving gel. As proteins elute from the column, they are trapped and concentrated in liquid phase in the collection chamber, free of the gel. The instrument is then paused at specific time intervals, and fractions are collected using a pipette. This process is repeated until all desired fractions have been collected. If fewer than 8 samples are run on a cartridge, any unused chambers can be used in subsequent separations.
This novel technology facilitates the quick and simple separation of up to 8 complex protein mixtures simultaneously, and offers several advantages when compared to previously available fractionation methods. This system is capable of fractionating up to 1mg of total protein per channel, for a total of 8mg per cartridge. Intact proteins over a broad mass range are separated on the basis of molecular weight, retaining important physiochemical properties of the analyte. The liquid phase entrapment provides for high recovery while eliminating the need for band or spot cutting, making the fractionation process highly reproducible1.

The accompanying video describes the use of the GELFREE 8100 Fractionation System, which partitions complex protein samples on the basis of molecular weight and recovers the fractions in liquid phase. The video describes how the technology works, how it is used, and provides resultant data, with polyacrylamide gel electrophoresis analysis of fractionated bovine liver homogenate.

液相恢复GELFREE 8100分馏系统使用基于分子量分馏

The GELFREE 8100 Fractionation System is a novel protein fractionation system designed to maximize protein recovery during molecular weight based ...

科研

生物学

Rapid Homogeneous Detection of Biological Assays Using Magnetic Modulation Biosensing System

A magnetic modulation biosensing system (MMB) [1,2] rapidly and homogeneously detected biological targets at low concentrations without any washing or separation step. When the IL-8 target was present, a 'sandwich'-based assay attached magnetic beads with IL-8 capture antibody to streptavidin coupled fluorescent protein via the IL-8 target and a biotinylated IL-8 antibody. The magnetic beads are maneuvered into oscillatory motion by applying an alternating magnetic field gradient through two electromagnetic poles. The fluorescent proteins, which are attached to the magnetic beads are condensed into the detection area and their movement in and out of an orthogonal laser beam produces a periodic fluorescent signal that is demodulated using synchronous detection. The magnetic modulation biosensing system was previously used to detect the coding sequences of the non-structural Ibaraki virus protein 3 (NS3) complementary DNA (cDNA) [2]. The techniques that are demonstrated in this work for external manipulation and condensation of particles may be used for other applications, e.g. delivery of magnetically-coupled drugs in-vivo or enhancing the contrast for in-vivo imaging applications.

Magnetic modulation biosensing system is utilized to rapidly, sensitively and simply detect biological assays, such as DNA molecules and proteins.

利用磁调制生物传感系统的生物检测的快速均质检测

A magnetic modulation biosensing system (MMB) [1,2] rapidly and homogeneously detected biological targets at low concentrations without any washing or ...

Bimolecular Fluorescence Complementation (BiFC) Assay for Protein-Protein Interaction in Onion Cells Using the Helios Gene Gun

Investigation of gene function in diverse organisms relies on knowledge of how the gene products interact with each other in their normal cellular environment. The Bimolecular Fluorescence Complementation (BiFC) Assay1 allows researchers to visualize protein-protein interactions in living cells and has become an essential research tool. This assay is based on the facilitated association of two fragments of a fluorescent protein (GFP) that are each fused to a potential interacting protein partner. The interaction of the two protein partners would facilitate the association of the N-terminal and C-terminal fragment of GFP, leading to fluorescence. For plant researchers, onion epidermal cells are an ideal experimental system for conducting the BiFC assay because of the ease in obtaining and preparing onion tissues and the direct visualization of fluorescence with minimal background fluorescence. The Helios Gene Gun (BioRad) is commonly used for bombarding plasmid DNA into onion cells. We demonstrate the use of Helios Gene Gun to introduce plasmid constructs for two interacting Arabidopsis thaliana transcription factors, SEUSS (SEU) and LEUNIG HOMOLOG (LUH)2 and the visualization of their interactions mediated by BiFC in onion epidermal cells.

Bimolecular Fluorescence Complementation BiFC Assay for Protein-Protein Interaction in Onion Cells Using the Helios Gene Gun

This article illustrates how to properly use the BioRad Helios Gene Gun to introduce plasmid DNA into onion epidermal cells and how to test for protein-protein interactions in onion cells based on the principle of Bimolecular Fluorescence Complementation (BiFC)

双分子荧光互补（附设）检测蛋白质相互作用的洋葱细胞使用的Helios基因枪

Investigation of gene function in diverse organisms relies on knowledge of how the gene products interact with each other in their normal cellular ...

In-vivo Detection of Protein-protein Interactions on Micro-patterned Surfaces

Unraveling the interaction network of molecules in-vivo is key to understanding the mechanisms that regulate cell function and metabolism. A multitude of methodological options for addressing molecular interactions in cells have been developed, but most of these methods suffer from being rather indirect and therefore hardly quantitative. On the contrary, a few high-end quantitative approaches were introduced, which however are difficult to extend to high throughput. To combine high throughput capabilities with the possibility to extract quantitative information, we recently developed a new concept for identifying protein-protein interactions (Schwarzenbacher et al., 2008). Here, we describe a detailed protocol for the design and the construction of this system which allows for analyzing interactions between a fluorophore-labeled protein ("prey") and a membrane protein ("bait") in-vivo. Cells are plated on micropatterned surfaces functionalized with antibodies against the bait exoplasmic domain. Bait-prey interactions are assayed via the redistribution of the fluorescent prey. The method is characterized by high sensitivity down to the level of single molecules, the capability to detect weak interactions, and high throughput capability, making it applicable as screening tool.

In-vivo Detection of Protein-protein Interactions on Micro-patterned Surfaces

This video shows experiments with subsequent analysis of protein-protein interactions by the use of micro-patterned surfaces. The approach offers the possibility to detect protein interactions in living cells and combines high throughput capabilities with the possibility to extract quantitative information.

微图案的表面上的蛋白质-蛋白质相互作用的体内检测

Unraveling the interaction network of molecules in-vivo is key to understanding the mechanisms that regulate cell function and metabolism. A multitude of ...

Bimolecular Fluorescence Complementation

Defining the subcellular distribution of signaling complexes is imperative to understanding the output from that complex. Conventional methods such as immunoprecipitation do not provide information on the spatial localization of complexes. In contrast, BiFC monitors the interaction and subcellular compartmentalization of protein complexes. In this method, a fluororescent protein is split into amino- and carboxy-terminal non-fluorescent fragments which are then fused to two proteins of interest. Interaction of the proteins results in reconstitution of the fluorophore (Figure 1)1,2. A limitation of BiFC is that once the fragmented fluorophore is reconstituted the complex is irreversible3. This limitation is advantageous in detecting transient or weak interactions, but precludes a kinetic analysis of complex dynamics. An additional caveat is that the reconstituted flourophore requires 30min to mature and fluoresce, again precluding the observation of real time interactions4. BiFC is a specific example of the protein fragment complementation assay (PCA) which employs reporter proteins such as green fluorescent protein variants (BiFC), dihydrofolate reductase, b-lactamase, and luciferase to measure protein:protein interactions5,6. Alternative methods to study protein:protein interactions in cells include fluorescence co-localization and F&ouml;rster resonance energy transfer (FRET)7. For co-localization, two proteins are individually tagged either directly with a fluorophore or by indirect immunofluorescence. However, this approach leads to high background of non-interacting proteins making it difficult to interpret co-localization data. In addition, due to the limits of resolution of confocal microscopy, two proteins may appear co-localized without necessarily interacting. With BiFC, fluorescence is only observed when the two proteins of interest interact. FRET is another excellent method for studying protein:protein interactions, but can be technically challenging. FRET experiments require the donor and acceptor to be of similar brightness and stoichiometry in the cell. In addition, one must account for bleed through of the donor into the acceptor channel and vice versa. Unlike FRET, BiFC has little background fluorescence, little post processing of image data, does not require high overexpression, and can detect weak or transient interactions. Bioluminescence resonance energy transfer (BRET) is a method similar to FRET except the donor is an enzyme (e.g. luciferase) that catalyzes a substrate to become bioluminescent thereby exciting an acceptor. BRET lacks the technical problems of bleed through and high background fluorescence but lacks the ability to provide spatial information due to the lack of substrate localization to specific compartments8. Overall, BiFC is an excellent method for visualizing subcellular localization of protein complexes to gain insight into compartmentalized signaling.

The subcellular localization of proteins is important in determining the spatio-temporal regulation of cell signaling. Here, we describe bimolecular fluorescence complementation (BiFC) as a straightforward method for monitoring the spatial interactions of proteins in the cell.

双分子荧光互补

Defining the subcellular distribution of signaling complexes is imperative to understanding the output from that complex. Conventional methods such as ...

A Protocol for the Identification of Protein-protein Interactions Based on 15N Metabolic Labeling, Immunoprecipitation, Quantitative Mass Spectrometry and Affinity Modulation

Protein-protein interactions are fundamental for many biological processes in the cell. Therefore, their characterization plays an important role in current research and a plethora of methods for their investigation is available1. Protein-protein interactions often are highly dynamic and may depend on subcellular localization, post-translational modifications and the local protein environment2. Therefore, they should be investigated in their natural environment, for which co-immunoprecipitation approaches are the method of choice3. Co-precipitated interaction partners are identified either by immunoblotting in a targeted approach, or by mass spectrometry (LC-MS/MS) in an untargeted way. The latter strategy often is adversely affected by a large number of false positive discoveries, mainly derived from the high sensitivity of modern mass spectrometers that confidently detect traces of unspecifically precipitating proteins. A recent approach to overcome this problem is based on the idea that reduced amounts of specific interaction partners will co-precipitate with a given target protein whose cellular concentration is reduced by RNAi, while the amounts of unspecifically precipitating proteins should be unaffected. This approach, termed QUICK for QUantitative Immunoprecipitation Combined with Knockdown4, employs Stable Isotope Labeling of Amino acids in Cell culture (SILAC)5 and MS to quantify the amounts of proteins immunoprecipitated from wild-type and knock-down strains. Proteins found in a 1:1 ratio can be considered as contaminants, those enriched in precipitates from the wild type as specific interaction partners of the target protein. Although innovative, QUICK bears some limitations: first, SILAC is cost-intensive and limited to organisms that ideally are auxotrophic for arginine and/or lysine. Moreover, when heavy arginine is fed, arginine-to-proline interconversion results in additional mass shifts for each proline in a peptide and slightly dilutes heavy with light arginine, which makes quantification more tedious and less accurate5,6. Second, QUICK requires that antibodies are titrated such that they do not become saturated with target protein in extracts from knock-down mutants.
Here we introduce a modified QUICK protocol which overcomes the abovementioned limitations of QUICK by replacing SILAC for 15N metabolic labeling and by replacing RNAi-mediated knock-down for affinity modulation of protein-protein interactions. We demonstrate the applicability of this protocol using the unicellular green alga Chlamydomonas reinhardtii as model organism and the chloroplast HSP70B chaperone as target protein7 (Figure 1). HSP70s are known to interact with specific co-chaperones and substrates only in the ADP state8. We exploit this property as a means to verify the specific interaction of HSP70B with its nucleotide exchange factor CGE19.

A Protocol for the Identification of Protein-protein Interactions Based on 15N Metabolic Labeling, Immunoprecipitation, Quantitative Mass Spectrometry and Affinity Modulation

We present a variation of the QUICK (QUantitative Immunoprecipitation Combined with Knockdown) approach that was introduced previously to distinguish between true and false protein-protein interactions. Our approach is based on 15N metabolic labeling, the modulation of affinities of protein-protein interactions by the presence/absence of ATP, immunoprecipitation, and quantitative mass spectrometry.

一个协议，用于基于蛋白质 - 蛋白质相互作用的鉴定<sup&gt; 15</sup&gt; N代谢标记，免疫沉淀法，的定量质谱法和亲和调制

Protein-protein interactions are fundamental for many biological processes in the cell. Therefore, their characterization plays an important role in ...

Glycan Profiling of Plant Cell Wall Polymers using Microarrays

Plant cell walls are complex matrixes of heterogeneous glycans which play an important role in the physiology and development of plants and provide the raw materials for human societies (e.g. wood, paper, textile and biofuel industries)1,2. However, understanding the biosynthesis and function of these components remains challenging.
Cell wall glycans are chemically and conformationally diverse due to the complexity of their building blocks, the glycosyl residues. These form linkages at multiple positions and differ in ring structure, isomeric or anomeric configuration, and in addition, are substituted with an array of non-sugar residues. Glycan composition varies in different cell and/or tissue types or even sub-domains of a single cell wall3. Furthermore, their composition is also modified during development1, or in response to environmental cues4.
In excess of 2,000 genes have Plant cell walls are complex matrixes of heterogeneous glycans been predicted to be involved in cell wall glycan biosynthesis and modification in Arabidopsis5. However, relatively few of the biosynthetic genes have been functionally characterized 4,5. Reverse genetics approaches are difficult because the genes are often differentially expressed, often at low levels, between cell types6. Also, mutant studies are often hindered by gene redundancy or compensatory mechanisms to ensure appropriate cell wall function is maintained7. Thus novel approaches are needed to rapidly characterise the diverse range of glycan structures and to facilitate functional genomics approaches to understanding cell wall biosynthesis and modification.
Monoclonal antibodies (mAbs)8,9 have emerged as an important tool for determining glycan structure and distribution in plants. These recognise distinct epitopes present within major classes of plant cell wall glycans, including pectins, xyloglucans, xylans, mannans, glucans and arabinogalactans. Recently their use has been extended to large-scale screening experiments to determine the relative abundance of glycans in a broad range of plant and tissue types simultaneously9,10,11.
Here we present a microarray-based glycan screening method called Comprehensive Microarray Polymer Profiling (CoMPP) (Figures 1 &amp; 2)10,11 that enables multiple samples (100 sec) to be screened using a miniaturised microarray platform with reduced reagent and sample volumes. The spot signals on the microarray can be formally quantified to give semi-quantitative data about glycan epitope occurrence. This approach is well suited to tracking glycan changes in complex biological systems12 and providing a global overview of cell wall composition particularly when prior knowledge of this is unavailable.

A technique called Comprehensive Microarray Polymer Profiling (CoMPP) for the characterisation of plant cell wall glycans is described. This method combines the specificity of monoclonal antibodies directed to defined glycan-epitopes with a miniature microarray analytical platform allowing screening of glycan occurrence in a broad range of biological contexts.

糖基谱研究植物细胞壁聚合物，用微阵列

Plant cell walls are complex matrixes of heterogeneous glycans which play an important role in the physiology and development of plants and provide the ...

Flow Cytometric Analysis of Bimolecular Fluorescence Complementation: A High Throughput Quantitative Method to Study Protein-protein Interaction

Among methods to study protein-protein interaction inside cells, Bimolecular Fluorescence Complementation (BiFC) is relatively simple and sensitive. BiFC is based on the production of fluorescence using two non-fluorescent fragments of a fluorescent protein (Venus, a Yellow Fluorescent Protein variant, is used here). Non-fluorescent Venus fragments (VN and VC) are fused to two interacting proteins (in this case, AKAP-Lbc and PDE4D3), yielding fluorescence due to VN-AKAP-Lbc-VC-PDE4D3 interaction and the formation of a functional fluorescent protein inside cells.
BiFC provides information on the subcellular localization of protein complexes and the strength of protein interactions based on fluorescence intensity. However, BiFC analysis using microscopy to quantify the strength of protein-protein interaction is time-consuming and somewhat subjective due to heterogeneity in protein expression and interaction. By coupling flow cytometric analysis with BiFC methodology, the fluorescent BiFC protein-protein interaction signal can be accurately measured for a large quantity of cells in a short time. Here, we demonstrate an application of this methodology to map regions in PDE4D3 that are required for the interaction with AKAP-Lbc. This high throughput methodology can be applied to screening factors that regulate protein-protein interaction.

Flow cytometric analysis of Bimolecular Fluorescence Complementation provides a high throughput quantitative method to study protein-protein interaction. This methodology can be applied to mapping protein binding sites and for screening factors that regulate protein-protein interaction.

双分子荧光互补流式细胞仪分析:高通量的定量方法研究蛋白质 - 蛋白质相互作用

Among methods to study protein-protein interaction inside cells, Bimolecular Fluorescence Complementation (BiFC) is relatively simple and sensitive. BiFC ...

Protein-protein Interactions Visualized by Bimolecular Fluorescence Complementation in Tobacco Protoplasts and Leaves

Many proteins interact transiently with other proteins or are integrated into multi-protein complexes to perform their biological function. Bimolecular fluorescence complementation (BiFC) is an in vivo method to monitor such interactions in plant cells. In the presented protocol the investigated candidate proteins are fused to complementary halves of fluorescent proteins and the respective constructs are introduced into plant cells via agrobacterium-mediated transformation. Subsequently, the proteins are transiently expressed in tobacco leaves and the restored fluorescent signals can be detected with a confocal laser scanning microscope in the intact cells. This allows not only visualization of the interaction itself, but also the subcellular localization of the protein complexes can be determined. For this purpose, marker genes containing a fluorescent tag can be coexpressed along with the BiFC constructs, thus visualizing cellular structures such as the endoplasmic reticulum, mitochondria, the Golgi apparatus or the plasma membrane. The fluorescent signal can be monitored either directly in epidermal leaf cells or in single protoplasts, which can be easily isolated from the transformed tobacco leaves. BiFC is ideally suited to study protein-protein interactions in their natural surroundings within the living cell. However, it has to be considered that the expression has to be driven by strong promoters and that the interaction partners are modified due to fusion of the relatively large fluorescence tags, which might interfere with the interaction mechanism. Nevertheless, BiFC is an excellent complementary approach to other commonly applied methods investigating protein-protein interactions, such as coimmunoprecipitation, in vitro pull-down assays or yeast-two-hybrid experiments.

Formation of protein complexes in vivo can be visualized by bimolecular fluorescence complementation. Interaction partners are fused to complementary parts of fluorescent tags and transiently expressed in tobacco leaves, resulting in a reconstituted fluorescent signal upon close proximity of the two proteins.

蛋白质 - 蛋白质相互作用的双分子荧光互补的烟草原生质体和叶片可视化

Many proteins interact transiently with other proteins or are integrated into multi-protein complexes to perform their biological function. Bimolecular ...

Investigating Protein-protein Interactions in Live Cells Using Bioluminescence Resonance Energy Transfer

Assays based on Bioluminescence Resonance Energy Transfer (BRET) provide a sensitive and reliable means to monitor protein-protein interactions in live cells. BRET is the non-radiative transfer of energy from a 'donor' luciferase enzyme to an 'acceptor' fluorescent protein. In the most common configuration of this assay, the donor is Renilla reniformis luciferase and the acceptor is Yellow Fluorescent Protein (YFP). Because the efficiency of energy transfer is strongly distance-dependent, observation of the BRET phenomenon requires that the donor and acceptor be in close proximity. To test for an interaction between two proteins of interest in cultured mammalian cells, one protein is expressed as a fusion with luciferase and the second as a fusion with YFP. An interaction between the two proteins of interest may bring the donor and acceptor sufficiently close for energy transfer to occur. Compared to other techniques for investigating protein-protein interactions, the BRET assay is sensitive, requires little hands-on time and few reagents, and is able to detect interactions which are weak, transient, or dependent on the biochemical environment found within a live cell. It is therefore an ideal approach for confirming putative interactions suggested by yeast two-hybrid or mass spectrometry proteomics studies, and in addition it is well-suited for mapping interacting regions, assessing the effect of post-translational modifications on protein-protein interactions, and evaluating the impact of mutations identified in patient DNA.

Interactions between proteins are fundamental to all cellular processes. Using Bioluminescence Resonance Energy Transfer, the interaction between a pair of proteins can be monitored in live cells and in real time. Furthermore, the effects of potentially pathogenic mutations can be assessed.

研究蛋白质 - 蛋白质相互作用活细胞使用生物发光共振能量转移

Assays based on Bioluminescence Resonance Energy Transfer (BRET) provide a sensitive and reliable means to monitor protein-protein interactions in live ...