Name: ultra-high-speed western blot using immunoreaction enhancing technology
Uploaded: 2020-09-26T13:00:00
Description: Watch this Scientific Journal Video about Ultra-High-Speed Western Blot using Immunoreaction Enhancing Technology at JoVE.com

This work was supported by the Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health. S.H. was supported by Japan Public-Private Partnership Student Study Abroad Program, and H.N. and K.Y. were by Valor and V Drug Overseas Training Scholarship.

1. SDS-PAGE and transfer to a PVDF membrane
<ol>
	<li>Perform SDS-PAGE to separate proteins based on relative size. 
	NOTE: Any commercial or home-made gel system is fine. Please follow the manufacturer&#8217;s protocol.</li>
	<li>Transfer separated proteins from a gel onto a PVDF membrane. 
	NOTE: Common transfer methods (semi-dry or wet transfer) are suitable. Please follow the manufacturer&#8217;s protocol.</li>
</ol>
2. Blocking of PVDF membranes
<ol>
	<li>Incubate the membranes ...

<ol>
	<li>MacPhee, D. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Methodological+considerations+for+improving+Western+blot+analysis.">Methodological considerations for improving Western blot analysis.</a> Journal of Pharmacol Toxicology Methods. 61 (2), 171-177 (2010).</li><li>Janes, K. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+analysis+of+critical+factors+for+quantitative+immunoblotting.">An analysis of critical factors for quantitative immunoblotting.</a> Science Signaling. 8 (371), (2015).</li><li>Schuck, P., Zhao, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+role+of+mass+transport+limitation+and+surface+heterogeneity+in+the+biophysical+characterization+of+macromolecular+binding+processes+by+SPR+biosensing.">The role of mass transport limitation and surface heterogeneity in the biophysical characterization of macromolecular binding processes by SPR biosensing.</a> Methods in Molecular Biology. 627, 15-54 (2010).</li><li>Li, J., Zrazhevskiy, P., Gao, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Eliminating+Size-Associated+Diffusion+Constraints+for+Rapid+On-Surface+Bioassays+with+Nanoparticle+Probes.">Eliminating Size-Associated Diffusion Constraints for Rapid On-Surface Bioassays with Nanoparticle Probes.</a> Small. 12 (8), 1035-1043 (2016).</li><li>Higashi, S. L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Old+but+not+Obsolete:+An+Enhanced+High+Speed+Immunoblot.">Old but not Obsolete: An Enhanced High Speed Immunoblot.</a> Journal of Biochemistry. 168 (1), 15-22 (2020).</li><li>Towbin, H., Staehelin, T., Gordon, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrophoretic+transfer+of+proteins+from+polyacrylamide+gels+to+nitrocellulose+sheets:+Procedure+and+some+applications.">Electrophoretic transfer of proteins from polyacrylamide gels to nitrocellulose sheets: Procedure and some applications.</a> Proceedings of the National Academy of Sciences of the United States of America. 76, 4350-4354 (1979).</li><li>Burnette, W. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term="Western+blotting":+electrophoretic+transfer+of+proteins+from+sodium+dodecyl+sulfate--polyacrylamide+gels+to+unmodified+nitrocellulose+and+radiographic+detection+with+antibody+and+radioiodinated+protein+A.">"Western blotting": electrophoretic transfer of proteins from sodium dodecyl sulfate--polyacrylamide gels to unmodified nitrocellulose and radiographic detection with antibody and radioiodinated protein A.</a> Analytical Biochemistry. 112 (2), 195-203 (1981).</li><li>Mishra, M., Tiwari, S., Gomes, A. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Protein+purification+and+analysis:+next+generation+Western+blotting+techniques.">Protein purification and analysis: next generation Western blotting techniques.</a> Expert Review of Proteomics. 14 (11), 1037-1053 (2017).</li><li>Ciaccio, M. F., Wagner, J. P., Chuu, C. P., Lauffenburger, D. A., Jones, R. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Systems+analysis+of+EGF+receptor+signaling+dynamics+with+microwestern+arrays.">Systems analysis of EGF receptor signaling dynamics with microwestern arrays.</a> Nature Methods. 7 (2), 148-155 (2010).</li><li>Treindl, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+bead-based+western+for+high-throughput+cellular+signal+transduction+analyses.">A bead-based western for high-throughput cellular signal transduction analyses.</a> Nature Communications. 7, 12852 (2016).</li><li>Sajjad, S., Do, M. T., Shin, H. S., Yoon, T. S., Kang, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+and+efficient+western+blot+assay+by+rotational+cyclic+draining+and+replenishing+procedure.">Rapid and efficient western blot assay by rotational cyclic draining and replenishing procedure.</a> Electrophoresis. 39 (23), 2974-2978 (2018).</li><li>Kurien, B. T., Scofield, R. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+brief+review+of+other+notable+protein+detection+methods+on+blots.">A brief review of other notable protein detection methods on blots.</a> Methods in Molecular Biology. 536, 557-571 (2009).</li><li>Nagase, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reliable+and+Sensitive+Detection+of+Glycosaminoglycan+Chains+with+Immunoblots.">Reliable and Sensitive Detection of Glycosaminoglycan Chains with Immunoblots.</a> Glycobiology. , (2020).</li></ol>

Western blot is a widely used analytical technique to detect specific proteins that was developed ~40 years ago7,8. Since then, the technique has continued to evolve, with subsequent innovations improving the sensitivity, speed, and quantitation of the technique2,9,10,11,12,<sup class="xref"...

A western blot (also known as an immunoblot) is a powerful and fundamental technique across a broad range of scientific and clinical disciplines. This technique is used to examine the presence, relative abundance, relative molecular mass, and post-translational modifications of proteins1. Combined with digital image analysis, this method can reliably analyze the abundance of proteins and protein modifications2. Although western blot is performed routinely, it is a time-consuming and labor intensive method. Long incubations of the antibody with membranes are required. Here, we describe a modification of the incubation method that overcomes this limitation without sacrificing sensitivity.
During incubation of the membrane, antibodies float in solution while antigens are immobilized on the membrane. Because of their high affinity, the rate of antibody binding to the antigen is faster than the diffusion of antibodies from the bulk solution to the membrane. This creates a low concentration &#8220;depletion layer&#8221; (Figure 1). It may take hours for more distant antibodies to reach the membrane via passive diffusion, which is the main factor responsible for long incubation times in this technique. This effect is called the mass transport limitation (MTL)3. It has been proposed that repetitive draining and replenishing the antibody-containing solution may disrupt the depletion layer and overcome MTL4. Here, we have devised a unique technique that implements this cyclic draining and replenishing (CDR) concept to diminish the effect of MTL in a traditional western blotting protocol and remarkedly shorten the required incubation period.
In order to maintain the detection sensitivity with a short incubation time, we made use of an immunoreaction enhancing technology that accelerates the antigen-antibody reaction, thereby improving the signal-to-noise ratio5. Many commercially available immunoreaction enhancing agents (IRE) consist of 2 components (Solution 1 and 2, see Table of Materials). The proprietary composition or mechanism of action of IRE has not been disclosed, but we have previously found that IRE decreased the dissociation constant between the antigen and antibody in solid phase binding assays, indicating increased affinity is, at least in part, responsible for the enhancing effect of IRE6. The combination of CDR with IRE yields an ultra-high-speed western blotting protocol that reduces the entire procedure time without sacrificing sensitivity.

<table>
	<tbody>
		<tr>
			<td>14 mL Round Bottom High Clarity PP Test Tube, Graduated, with Snap Cap</td>
			<td>Falcon</td>
			<td>352059</td>
			<td></td>
		</tr>
		<tr>
			<td>Apollo Transparency Film for Laser Printers</td>
			<td>N/A</td>
			<td>N/A</td>
			<td>Any kinds of Laser Printer Transparency Film are fine.</td>
		</tr>
		<tr>
			<td>Azure Imaging System 600</td>
			<td>Azure Biosystems</td>
			<td>Azure 600</td>
			<td>Any kind of Image Acquiring Sytem is fine for chemiluminescent and/or fluorescent detection.</td>
		</tr>
		<tr>
			<td>Can Get Signal Immunoreaction Enhancer Solution</td>
			<td>TOYOBO</td>
			<td>NKB-101</td>
			<td></td>
		</tr>
		<tr>
			<td>CARNATION Instant Nonfat Dry Milk</td>
			<td>Carnation</td>
			<td>N/A</td>
			<td></td>
		</tr>
		<tr>
			<td>ECL anti-mouse IgG, Horseradish peroxidase linked F(ab&#8217;)2 fragment from sheep</td>
			<td>GE Healthcare</td>
			<td>NA9310V</td>
			<td></td>
		</tr>
		<tr>
			<td>ECL anti-rabbit IgG, Horseradish peroxidase linked F(ab&#8217;)2 fragment from donkey</td>
			<td>GE Healthcare</td>
			<td>NA9340V</td>
			<td></td>
		</tr>
		<tr>
			<td>HYBAID Micro-4</td>
			<td>N/A</td>
			<td>N/A</td>
			<td>Any hybridization oven is fine as long as the tubes are rotated evenly at a horizontal position.</td>
		</tr>
		<tr>
			<td>Immobilon-P PVDF Membrane, 0.45 &#181;m pore size</td>
			<td>Millipore Sigma</td>
			<td>IPVH304F0</td>
			<td></td>
		</tr>
		<tr>
			<td>IRDye 680RD Goat anti-Mouse IgG Secondary Antibody</td>
			<td>LICOR</td>
			<td>926-68070</td>
			<td></td>
		</tr>
		<tr>
			<td>IRDye 800CW Goat anti-Rabbit IgG Secondary Antibody</td>
			<td>LICOR</td>
			<td>926-32211</td>
			<td></td>
		</tr>
		<tr>
			<td>KPL LumiGLO Reserve Chemiluminescent Substrate</td>
			<td>seracare</td>
			<td>5430-0049</td>
			<td></td>
		</tr>
		<tr>
			<td>Mouse anti-&#223; actin antibody</td>
			<td>Millipore Sigma</td>
			<td>A5316</td>
			<td></td>
		</tr>
		<tr>
			<td>Odyssey Blocking Buffer (PBS)</td>
			<td>LICOR</td>
			<td>927-40100</td>
			<td>Blocking Buffer for fluorescent detection</td>
		</tr>
		<tr>
			<td>OXO Salad Spinner</td>
			<td>OXO</td>
			<td>32480V2B</td>
			<td>Any salad spinner is fine as long as the PVDF membranes are rinsed vigorously without tear.</td>
		</tr>
		<tr>
			<td>Parafilm Sealing Film</td>
			<td>Bemis</td>
			<td>Parafilm M PM996</td>
			<td>semi-transparent flexible film</td>
		</tr>
		<tr>
			<td>Polyethylene Flat-Top Screw Caps for 50 mL Conical Bottom Centrifuge Tubes</td>
			<td>Falcon</td>
			<td>352070</td>
			<td></td>
		</tr>
		<tr>
			<td>Rings to hold 14 ml tube in the center of 50 ml tube</td>
			<td>N/A</td>
			<td>N/A</td>
			<td>Prepared in a machine shop</td>
		</tr>
		<tr>
			<td>Rabbit anti-6X His tag antibody</td>
			<td>Abcam</td>
			<td>ab9108</td>
			<td></td>
		</tr>
		<tr>
			<td>Tween20</td>
			<td>Millipore Sigma</td>
			<td>P2287</td>
			<td></td>
		</tr>
	</tbody>
</table>

ultra-high-speed western blot using immunoreaction enhancing technology

A western blot (also known as an immunoblot) is a canonical method for biomedical research. It is commonly used to determine the relative size and abundance of specific proteins as well as post-translational protein modifications. This technique has a rich history and remains in widespread use due to its simplicity. However, the western blotting procedure famously takes hours, even days, to complete, with a critical bottleneck being the long incubation times that limit its throughput. These incubation steps are required due to the slow diffusion of antibodies from the bulk solution to the immobilized antigens on the membrane: the antibody concentration near the membrane is much lower than the bulk concentration. Here, we present an innovation that dramatically reduces these incubation intervals by improving antigen binding via cyclic draining and replenishing (CDR) of the antibody solution. We also utilized an immunoreaction enhancing technology to preserve the sensitivity of the assay. A combination of the CDR method with a commercial immunoreaction enhancing agent boosted the output signal and substantially reduced the antibody incubation time. The resulting ultra-high-speed western blot can be accomplished in 20 minutes without any loss in sensitivity. This method can be applied to western blots using both chemiluminescent and fluorescent detection. This simple protocol allows researchers to better explore the analysis of protein expression in many samples.

This example illustrates the effectiveness of the CDR method together with immunoenhancing technology on western blot. Static incubation was performed on a semi-transparent flexible film where PVDF membranes were incubated with the antibody solution, whereas CDR incubation was in a hybridization oven by rotating tubes that contained the membranes and the antibody solution (Movie). Figure 2 showed quantities of antigen and antibody, respectively, necessary for chemiluminescent detection on we...

Watch this Scientific Journal Video about Ultra-High-Speed Western Blot using Immunoreaction Enhancing Technology at JoVE.com

Ultra-High-Speed Western Blot using Immunoreaction Enhancing Technology

An ultra-high-speed western blotting technique is developed by improving the kinetics of antigen-antibody binding through cyclic draining and replenishing (CDR) technology in conjunction with an immunoreaction enhancing agent.

A western blot (also known as an immunoblot) is a canonical method for biomedical research. It is commonly used to determine the relative size and ...

Western blotting is an established method that detects antigens on a transferred membrane and is commonly used in biomedical research, but it takes hours or days to complete the entire procedure. Using the combination of immuno-enhancing technology with cyclic draining and replenishing, once you've got a block membrane, the entire procedure can be accomplished in as little as 20 minutes without sacrificing sensitivity. Because Western blotting is common to many different research areas, it has broad applicability to speed up research.The successful use of this protocol relies on the optimization of antibody dilution with immunoreaction enhancing reagent and incubation time. Begin by incubating the PVDF membranes in appropriate blocking buffers for one hour with agitation at room temperature. While the membranes are incubating, prepare 10%immunoreaction enhancing agent one solution or IRE1 with distilled water and vortex it well, then dilute the primary antibody with 10%IRE1, mixing it gently and thoroughly.Pick up the PVDF membrane with tweezers and briefly drain the blocking solution. Insert the membrane into a conical tube with primary antibody, ensuring that the entire membrane adheres to the wall of the tube and that the side of the membrane that was originally in contact with the gel is facing inward. Cap the tube tightly.Insert the tube into a glass bottle for the hybridization oven and turn on the oven. Incubate the membrane with six RPM rotation for at least five minutes. Stop the rotation and carefully remove the PVDF membrane from the tube with tweezers.Place the membrane into a container with 50 milliliters of PBST and rinse it, then rinse it in a container with distilled water until no bubbles appear, which will remove the majority of the antibody. Transfer the membrane to a salad spinner that contains 250 milliliters of PBST. Place the strainer basket in the spinner and ensure that the lid has been put on securely, then activate the spinner and run it for 20 to 30 seconds.Discard the solution and briefly rinse the inside of the spinner with distilled water. Add 250 milliliters of PBST into the spinner and repeat the spin, then incubate the membrane with the secondary antibodies and wash it again as described in the text manuscript. Place a piece of semi-transparent flexible film on a flat surface.Mix two components of the chemiluminescent substrate in a five milliliter tube and immediately transfer 1.5 milliliters of the mixed substrate to the semi-transparent film. Place the PVDF membrane on the solution and transfer the rest of the substrate solution onto the membrane. Incubate the PVDF membrane with the mixed substrate for one minute.Pick up the PVDF membrane with tweezers and drain the substrate solution briefly. Sandwich the membrane between a pair of transparency films and image it under chemiluminescent mode. The quantities of antigen and antibody respectively necessary for chemiluminescent detection of Western blot are shown here.In both static and CDR incubations, usage of IRE solutions increased the sensitivity. Similarly, the minimum concentration of anti-6s His tag antibody was lowered from 100 to 50 nanograms per milliliter under static conditions and from 100 to 12.5 nanograms per milliliter under CDR conditions. CDR incubation for either 5 or 10 minutes dramatically lowered the detection limit compared to static incubation.Furthermore, the combination of CDR with IRE revealed superior sensitivity on the Western blot, even within the extremely short incubation period. Successful application of this method to a Western blot with fluorescent detection is demonstrated here. Fluorescent detection in contrast to chemiluminescent detection has the unique ability to detect multiple targets on the same blot at the same time without stripping and reprobing antibodies.His-tagged alkaline phosphatase and beta-actin in the cell lysates were simultaneously detected using a two-color fluorophore. CDR incubation with IRE not only accelerated the detection, but also increased the sensitivity. During the incubation, the membrane should stay attached to the wall of the tube.The tube should be rotated horizontally so that solution washes continually over the membrane surface. This protocol significantly accelerated our research productivity, which strongly depends on Western blotting procedures.

ultra-high-speed-western-blot-using-immunoreaction-enhancing

Research

JoVE Journal

Biochemistry

Using Scaffold Liposomes to Reconstitute Lipid-proximal Protein-protein Interactions In Vitro

Studies of integral membrane proteins in vitro are frequently complicated by the presence of a hydrophobic transmembrane domain. Further complicating these studies, reincorporation of detergent-solubilized membrane proteins into liposomes is a stochastic process where protein topology is impossible to enforce. This paper offers an alternative method to these challenging techniques that utilizes a liposome-based scaffold. Protein solubility is enhanced by deletion of the transmembrane domain, and these amino acids are replaced with a tethering moiety, such as a His-tag. This tether interacts with an anchoring group (Ni2+ coordinated by nitrilotriacetic acid (NTA(Ni2+)) for His-tagged proteins), which enforces a uniform protein topology at the surface of the liposome. An example is presented wherein the interaction between Dynamin-related protein 1 (Drp1) with an integral membrane protein, Mitochondrial Fission Factor (Mff), was investigated using this scaffold liposome method. In this work, we have demonstrated the ability of Mff to efficiently recruit soluble Drp1 to the surface of liposomes, which stimulated its GTPase activity. Moreover, Drp1 was able to tubulate the Mff-decorated lipid template in the presence of specific lipids. This example demonstrates the effectiveness of scaffold liposomes using structural and functional assays and highlights the role of Mff in regulating Drp1 activity.

Using Scaffold Liposomes to Reconstitute Lipid-proximal Protein-protein Interactions In Vitro

This paper describes a method for assessing the interactions and assemblies of integral membrane proteins in vitro with various partner factors in a lipid-proximal environment.

Studies of integral membrane proteins in vitro are frequently complicated by the presence of a hydrophobic transmembrane domain. Further complicating ...

A Western Blotting Protocol for Small Numbers of Hematopoietic Stem Cells

Hematopoietic stem cells (HSCs) are rare cells, with the mouse bone marrow containing only ~25,000 phenotypic long term repopulating HSCs. A Western blotting protocol was optimized and suitable for the analysis of small numbers of HSCs (500 - 15,000 cells). Phenotypic HSCs were purified, accurately counted, and directly lysed in Laemmli sample buffer. Lysates containing equal numbers of cells were analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), and the blot was prepared and processed following standard Western blotting protocols. Using this protocol, 2,000 - 5,000 HSCs can be routinely analyzed, and in some cases data can be obtained from as few as 500 cells, compared to the 20,000 to 40,000 cells reported in most publications. This protocol should be generally applicable to other hematopoietic cells, and enables the routine analysis of small numbers of cells using standard laboratory procedures.

A standard Western blotting protocol was optimized for analyzing as few as 500 hematopoietic stem or progenitor cells. Optimization involves careful handling of the cell sample, limiting transfers between tubes, and directly lysing the cells in Laemmli sample buffer.

Hematopoietic stem cells (HSCs) are rare cells, with the mouse bone marrow containing only ~25,000 phenotypic long term repopulating HSCs. A Western ...

High Throughput, Absolute Determination of the Content of a Selected Protein at Tissue Levels Using Quantitative Dot Blot Analysis (QDB)

Lacking a convenient, quantitative, high throughput immunoblot method for absolute determination of the content of a specific protein at cellular and tissue level significantly hampers the progress in proteomic research. Results derived from currently available immunoblot techniques are also relative, preventing any efforts to combine independent studies with a large-scale analysis of protein samples. In this study, we demonstrate the process of quantitative dot blot analysis (QDB) to achieve absolute quantification in a high throughput format. Using a commercially available protein standard, we are able to determine the absolute content of capping actin protein, gelsolin-like (CAPG) in protein samples prepared from three different mouse tissues (kidney, spleen, and prostate) together with a detailed explanation of the experimental details. We propose the QDB analysis as a convenient, quantitative, high throughput immunoblot method of absolute quantification of individual proteins at the cellular and tissue level. This method will substantially aid biomarker validation and pathway verification in various areas of biological and biomedical research.

High Throughput, Absolute Determination of the Content of a Selected Protein at Tissue Levels Using Quantitative Dot Blot Analysis QDB

Here we demonstrate a detailed process of quantitative dot blot analysis (QDB) by determining the absolute content of a targeted protein, capping actin protein, gelsolin-like (CAPG), in three different mouse tissues. We demonstrate a high throughput, convenient, quantitative immunoblot technique for biomarker validation at the cellular and tissue level.

Lacking a convenient, quantitative, high throughput immunoblot method for absolute determination of the content of a specific protein at cellular and ...

Robust Comparison of Protein Levels Across Tissues and Throughout Development Using Standardized Quantitative Western Blotting

Western blotting is a technique that is commonly used to detect and quantify protein expression. Over the years, this technique has led to many advances in both basic and clinical research. However, as with many similar experimental techniques, the outcome of Western blot analyses is easily influenced by choices made in the design and execution of the experiment. Specific housekeeping proteins have traditionally been used to normalize protein levels for quantification, however, these have a number of limitations and have therefore been increasingly criticized over the past few years. Here, we describe a detailed protocol that we have developed to allow us to undertake complex comparisons of protein expression variation across different tissues, mouse models (including disease models), and developmental timepoints. By using a fluorescent total protein stain and introducing the use of an internal loading standard, it is possible to overcome existing limitations in the number of samples that can be compared within experiments and systematically compare protein levels across a range of experimental conditions. This approach expands the use of traditional western blot techniques, thereby allowing researchers to better explore protein expression across different tissues and samples.

This method describes a robust and reproducible approach for the comparison of protein levels in different tissues and at different developmental timepoints using a standardized quantitative western blotting approach.

Western blotting is a technique that is commonly used to detect and quantify protein expression. Over the years, this technique has led to many advances ...

Identification of Inositol Phosphate or Phosphoinositide Interacting Proteins by Affinity Chromatography Coupled to Western Blot or Mass Spectrometry

Inositol phosphates and phosphoinositides regulate several cellular processes in eukaryotes, including gene expression, vesicle trafficking, signal transduction, metabolism, and development. These metabolites perform this regulatory activity by binding to proteins, thereby changing protein conformation, catalytic activity, and/or interactions. The method described here uses affinity chromatography coupled to mass spectrometry or Western blotting to identify proteins that interact with inositol phosphates or phosphoinositides. Inositol phosphates or phosphoinositides are chemically tagged with biotin, which is then captured via streptavidin conjugated to agarose or magnetic beads. Proteins are isolated by their affinity of binding to the metabolite, then eluted and identified by mass spectrometry or Western blotting. The method has a simple workflow that is sensitive, non-radioactive, liposome-free, and customizable, supporting the analysis of protein and metabolite interaction with precision. This approach can be used in label-free or in amino acid-labelled quantitative mass spectrometry methods to identify protein-metabolite interactions in complex biological samples or using purified proteins. This protocol is optimized for the analysis of proteins from Trypanosoma brucei, but it can be adapted to related protozoan parasites, yeast or mammalian cells.

This protocol focuses on the identification of proteins that bind to inositol phosphates or phosphoinositides. It uses affinity chromatography with biotinylated inositol phosphates or phosphoinositides that are immobilized via streptavidin to agarose or magnetic beads. Inositol phosphate or phosphoinositide binding proteins are identified by Western blotting or mass spectrometry.

Inositol phosphates and phosphoinositides regulate several cellular processes in eukaryotes, including gene expression, vesicle trafficking, signal ...

RNA Blot Analysis for the Detection and Quantification of Plant MicroRNAs

MicroRNAs (miRNAs) are a class of endogenously expressed non-coding, ~21 nt small RNAs involved in the regulation of gene expression in both plants and animals. Most miRNAs act as negative switches of gene expression targeting key genes. In plants, primary miRNAs (pri-miRNAs) transcripts are generated by RNA polymerase II, and they form varying lengths of stable stem-loop structures called pre-miRNAs. An endonuclease, Dicer-like1, processes the pre-miRNAs into miRNA-miRNA* duplexes. One of the strands from miRNA-miRNA* duplex is selected and loaded onto Argonaute 1 protein or its homologs to mediate the cleavage of target mRNAs. Although miRNAs are key signaling molecules, their detection is often carried out by less than optimal PCR-based methods instead of a sensitive northern blot analysis. We describe a simple, reliable, and extremely sensitive northern method that is ideal for the quantification of miRNA levels with very high sensitivity, literally from any plant tissue. Additionally, this method can be used to confirm the size, stability and the abundance of miRNAs and their precursors.

This method demonstrates use of the northern hybridization technique to detect miRNAs from total RNA extract.

MicroRNAs (miRNAs) are a class of endogenously expressed non-coding, ~21 nt small RNAs involved in the regulation of gene expression in both plants and ...

Exploring Biomolecular Interaction Between the Molecular Chaperone Hsp90 and Its Client Protein Kinase Cdc37 using Field-Effect Biosensing Technology

Biomolecular interactions play versatile roles in numerous cellular processes&#160;by regulating and coordinating functionally relevant biological events. Biomolecules such as proteins, carbohydrates, vitamins, fatty acids, nucleic acids, and enzymes are fundamental building blocks of living beings; they assemble into complex networks in biosystems to synchronize a myriad of life events. Proteins typically utilize complex interactome networks to carry out their functions; hence it is mandatory to evaluate such interactions to unravel their importance in cells at both cellular and organism levels. Toward this goal, we introduce a rapidly emerging technology, field-effect biosensing (FEB), to determine specific biomolecular interactions. FEB is a benchtop, label-free, and reliable biomolecular detection technique to determine specific interactions and uses high-quality electronic-based biosensors. The FEB technology can monitor interactions in the nanomolar range due to the biocompatible nanomaterials used on its biosensor surface. As a proof of concept, the protein-protein interaction (PPI) between heat shock protein 90 (Hsp90) and cell division cycle 37 (Cdc37) was elucidated. Hsp90 is an ATP-dependent molecular chaperone that plays an essential role in the folding, stability, maturation, and quality control of many proteins, thereby regulating multiple vital cellular functions. Cdc37 is regarded as a protein kinase-specific molecular chaperone, as it specifically recognizes and recruits protein kinases to Hsp90 to regulate their downstream signal transduction pathways. As such, Cdc37 is considered a co-chaperone of Hsp90. The chaperone-kinase pathway (Hsp90/Cdc37 complex) is hyper-activated in multiple malignancies promoting cellular growth; therefore, it is a potential target for cancer therapy. The present study demonstrates the efficiency of FEB technology using the Hsp90/Cdc37 model system. FEB detected a strong PPI between the two proteins (KD values of 0.014 &#181;M, 0.053 &#181;M, and 0.072 &#181;M in three independent experiments). In summary, FEB is a label-free and cost-effective PPI detection platform, which offers fast and accurate measurements.

Field-effect biosensing (FEB) is a label-free technique for detecting biomolecular interactions. It measures the electric current through the graphene biosensor to which the binding targets are immobilized. The FEB technology was used to evaluate biomolecular interactions between Hsp90 and Cdc37 and a strong interaction between the two proteins was detected.

Biomolecular interactions play versatile roles in numerous cellular processes&#160;by regulating and coordinating functionally relevant biological events. ...

The Peel-Blot Technique: A Cryo-EM Sample Preparation Method to Separate Single Layers From Multi-Layered or Concentrated Biological Samples

The peel-blot cryo-EM grid preparation technique is a significantly modified back-injection method with the objective of achieving a reduction in layers of multi-layered samples. This removal of layers prior to plunge freezing can aid in reducing sample thickness to a level suitable for cryo-EM data collection, improving sample flatness, and facilitating image processing. The peel-blot technique allows for the separation of multilamellar membranes into single layers, of layered 2D crystals into individual crystals, and of stacked, sheet-like structures of soluble proteins to likewise be separated into single layers. The high sample thickness of these types of samples frequently poses insurmountable problems for cryo-EM data collection and cryo-EM image processing, especially when the microscope stage must be tilted for data collection. Furthermore, grids of high concentrations of any of these samples can be prepared for efficient data collection since sample concentration prior to grid preparation can be increased and the peel-blot technique adjusted to result in a dense distribution of single-layered specimen.

The peel-blot technique is a cryo-EM grid preparation method that allows for the separation of multilayered and concentrated biological samples into single layers to reduce thickness, increase sample concentration, and facilitate image processing.

The peel-blot cryo-EM grid preparation technique is a significantly modified back-injection method with the objective of achieving a reduction in layers ...

Study of the Functions and Activities of Neuronal K-Cl Co-Transporter KCC2 Using Western Blotting

Potassium chloride cotransporters 2 (KCC2) is a member of the solute carrier family 12 (SLC12) of cation-chloride-cotransporters (CCCs), found exclusively in the neuron and is essential for the proper functioning of Cl- homeostasis and consequently functional GABAergic inhibition. Failure in proper regulation of KCC2 is deleterious and has been associated with the prevalence of several neurological diseases, including epilepsy. There has been considerable progress with regard to understanding the mechanisms involved in the regulation of KCC2, accredited to the development of techniques that enable researchers to study its functions and activities; either via direct (assessing kinase regulatory sites phosphorylation) or indirect (observing and monitoring GABA activity) investigations. Here, the protocol highlights how to investigate KCC2 phosphorylation at kinase regulatory sites - Thr906 and Thr1007- using western blotting technique. There are other classic methods used to directly measure KCC2 activity, such as rubidium ion and thallium ion uptake assay. Further techniques such as patch-clamp-electrophysiology are used to measure GABA activity; hence, indirectly reflecting activated and/or inactivated KCC2 as informed by the assessment of intracellular chloride ion homeostasis. A few of these additional techniques will be briefly discussed in this manuscript.

The present protocol highlights the application of western blotting technique to study the functions and activities of neuronal K-Cl co-transporter KCC2. The protocol describes the investigation of KCC2 phosphorylation at kinase regulatory sites Thr906/1007 via western blotting. Also, additional methods to confirm KCC2 activity are briefly highlighted in this text.

Potassium chloride cotransporters 2 (KCC2) is a member of the solute carrier family 12 (SLC12) of cation-chloride-cotransporters (CCCs), found exclusively ...

Western Blotting of Digested DNA Samples Containing DNA-Protein Crosslinks (DPCs)

To begin the western blotting of the normalized digested DNA samples, add 4X Laemmli sample buffer and boil the sample for five minutes. Load five to six micrograms of digested sample onto 4 to 20%polyacrylamide gel and perform SDS-PAGE to resolve unmodified and post-translational modifications or PMT conjugated DPCs. Incubate the gel with Coomassie blue stain overnight at room temperature.Wash the gel with double distilled water for two hours before image acquisition. To detect ubiquitylation, SUMO-1 or SUMO-2 and 3 modification, ADP ribosylation, total TOP1, TOP2 alpha, or TOP2 beta DPCs, dilute the corresponding antibodies as shown in the table. Next, transfer the gel in an appropriate dilution of primary antibody in blocking buffer and incubate the membranes overnight at four degrees Celsius.Once done, incubate PBST washed membrane with a secondary antibody diluted 5, 000 fold in blocking buffer for 60 minutes at room temperature before developing the membrane with enhanced chemiluminescence reagent. Acquire an image using the imaging system. The camptothecin exposure induced TOP1 DPCs formation.The TOP1 DPCs formation peaked after 20 minutes of camptothecin exposure similar to the anti-SUMO-2 and 3 modification. The culmination of SUMO-1 modification and ubiquitylation was also observed. DPCs and their SUMO-2 and 3 TOP1 modifications diminished in a camptothecin dose dependent manner.Adipocyte-induced TOP2 DPCs and SUMO-2 and 3 modification reached to peak at 20 minutes and then decreased. In comparison, SUMO-1 and ubiquitin modifications peaked at 60 minutes. The formaldehyde-induced DPCs and their SUMO-2 and 3, SUMO-1, and ubiquitylation formed and accumulated in a dose dependent manner.The quantitative detection of PARylation of TOP1 DPCs using an anti-PAR antibody, TOP1 DPC PARylation was not detectable unless a PARG inhibitor was added to the cell, suggesting that PARylation transpires promptly and is highly dynamic.