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 in appropriate blocking buffers for 1 h with agitation at room temperature. 
	NOTE: Depending on the primary antibody and detection system, an appropriate blocking buffer should be selected. For example, the most typical blockers are BSA, nonfat dry milk, casein, and commercial synthetic polymers. PBS and/or TBS with 0.1% Tween20 are the most commonly used buffers. This blocking step may be done overnight at 4 &#730;C.</li>
</ol>
3. Incubation with primary antibody
<ol>
	<li>Prepare 10% immunoreaction enhancing agent-1 solution (IRE-1) with distilled water. Vortex well.</li>
	<li>Prepare the diluted primary antibody with 10% IRE-1. Mix it gently and thoroughly.</li>
	<li>If using a larger membrane (4 cm x 8 cm &#8211; 8 cm x 8 cm), add 8 mL of the antibody solution into 50 mL conical centrifuge tubes. If using a smaller membrane (2 cm x 8 cm &#8211; 4 cm x 8 cm), add 3 mL of the antibody solution into 14 mL round-bottom polypropylene tube (Table of Materials).</li>
	<li>Pick up the PVDF membrane with tweezers and drain the blocking solution briefly. Insert the PVDF membrane into this tube with gloved fingers and ensure that the entire membrane adheres to the wall of the tube. When the PVDF membrane is inserted into a tube, face the &#8220;protein side&#8221; of the membrane that was originally in contact with the gel inward. Close the cap tightly.</li>
	<li>Insert the 50 mL tube into a glass bottle for the hybridization oven. 
	NOTE: When 14 mL tubes are used for this incubation, insert a 14 mL tube into the 50 mL tube, using a pair of plastic ring holders to keep the inner tube in the center of the 50 mL tube.</li>
	<li>Turn on the hybridization oven.</li>
	<li>Incubate the membrane with 6 rpm rotation for at least 5 min. 
	NOTE: Make sure that the membrane adheres to the wall at all times and that the (inner) tube is horizontal to cover the membrane with the antibody solution evenly. Calibrate the dilution of the antibody and incubation time prior to the actual experiment.</li>
</ol>
4. Membrane wash
<ol>
	<li>Stop the rotation.</li>
	<li>Carefully remove the PVDF membrane from the tube with tweezers, and place the membrane into a container with 50 mL of PBS-T.</li>
	<li>Rinse the membrane briefly with PBS-T.</li>
	<li>Rinse the membrane in the container with distilled water until no bubbles appear. This is to remove the majority of the antibody.</li>
	<li>Transfer the PVDF membrane from the container to the salad spinner that contains 250 mL of PBS-T.</li>
	<li>Place the strainer basket in the spinner. Ensure that the lid has been put on securely.</li>
	<li>Activate the spinner and run it for about 20-30 s.</li>
	<li>Discard the solution and briefly rinse the inside of the spinner with distilled water.</li>
	<li>Add 250 mL of PBS-T into the spinner again.</li>
	<li>Repeat steps 4.6 and 4.7.</li>
</ol>
5. Incubation with the secondary antibody
<ol>
	<li>Prepare 10% immunoreaction enhancing agent-2 solution (IRE-2) with distilled water. Vortex well.</li>
	<li>Prepare the diluted secondary antibody with 10% IRE-2. Mix it gently and thoroughly.</li>
	<li>Select the volume of the antibody solution and tube as stated in step 3.3.</li>
	<li>Pick up the PVDF membrane with tweezers and drain the solution briefly. Insert the PVDF membrane into the tube as stated in step 3.4.</li>
	<li>Insert the 50 mL tube into a glass bottle for the hybridization oven.</li>
	<li>Turn on the hybridization oven.</li>
	<li>Incubate the membrane with 6 rpm rotation for at least 5 min. Make sure that the membrane adheres to the wall at all times and that the (inner) tube is horizontal to evenly cover the membrane with the antibody solution. 
	NOTE: Calibrate the incubation time prior to the actual experiment. When the secondary antibody is fluorescently conjugated, perform the incubation in the dark.</li>
</ol>
6. Membrane wash
<ol>
	<li>Follow steps 4.1 to 4.10.</li>
</ol>
7. Image acquisition
<ol>
	<li>Chemiluminescent detection
	<ol>
		<li>Place a piece of semi-transplant flexible film (10 cm x 15 cm) on a flat surface.</li>
		<li>Mix 2 components of the chemiluminescent substrate in a 5&#160;mL tube.</li>
		<li>Immediately transfer 1.5 mL of the mixed substrate to the semi-transplant flexible film and place the PVDF membrane upon it. Then, transfer the rest of the substrate solution onto the membrane.</li>
		<li>Incubate the PVDF membrane with the mixed substrate on a semi-transparent flexible film for 1 min.</li>
		<li>Pick up the PVDF membrane with tweezers and drain the substrate solution briefly.</li>
		<li>Sandwich the membrane between a pair of transparency films.</li>
		<li>Acquire the image under chemiluminescent mode.</li>
	</ol>
	</li>
	<li>Fluorescent detection
	<ol>
		<li>Pick up the PVDF membrane with tweezers and drain the&#160;solution briefly.</li>
		<li>Sandwich the membrane between a pair of transparency films.</li>
		<li>Acquire the image under fluorescent mode. 
		NOTE: Steps 7.1 and 7.2 should be performed in close proximity to the imaging machine to ensure maximum sensitivity.</li>
		<li>When the background signal is high, perform a washing step in a container with 80-100 mL of PBS-T: 10 min rinse 3 times for the primary antibody and 5 min rinse 6 times for the secondary antibody. 
		NOTE: Both primary and secondary antibodies diluted with 10% IRE solutions can be used up to 8-10 times without loss of sensitivity6. The solution should be kept at 4 &#176;C for up to 1 month.</li>
	</ol>
	</li>
</ol>

<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>

The authors have declared no competing interests directly relevant to the contents of this article.

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 ...

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

Research

JoVE Journal

Biochemistry

5.8K Views.  National Institutes of Health. 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.

Video: Ultra-High-Speed Western Blot using Immunoreaction Enhancing Technology

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 ...

Studying Protein Import into Chloroplasts Using Protoplasts

The chloroplast is an essential organelle that is responsible for various cellular processes in plants, such as photosynthesis and the production of many secondary metabolites and lipids. Chloroplasts require a large number of proteins for these various physiological processes. Over 95% of chloroplast proteins are nucleus-encoded and imported into chloroplasts from the cytosol after translation on cytosolic ribosomes. Thus, the proper import or targeting of these nucleus-encoded chloroplast proteins to chloroplasts is essential for the proper functioning of chloroplasts as well as the plant cell. Nucleus-encoded chloroplast proteins contain signal sequences for specific targeting to chloroplasts. Molecular machinery localized to the chloroplast or cytosol recognize these signals and carry out the import process. To investigate the mechanisms of protein import or targeting to chloroplasts in vivo, we developed a rapid, efficient protoplast-based method to analyze protein import into chloroplasts of Arabidopsis. In this method, we use protoplasts isolated from leaf tissues of Arabidopsis. Here, we provide a detailed protocol for using protoplasts to investigate the mechanism by which proteins are imported into chloroplasts.

Here we describe a protocol to express proteins into protoplasts by using PEG-mediated transformation method. The method provides easy expression of proteins of interest, and efficient investigation of protein localization and the import process for various experimental conditions in vivo.

The chloroplast is an essential organelle that is responsible for various cellular processes in plants, such as photosynthesis and the production of many ...

Cortisol Measurement in Koala (Phascolarctos cinereus) Fur

Optimal methods of hormone extraction used to measure stress in animals across sample types are not always the same. Australia&#39;s iconic marsupial species, the koala (Phascolarctos cinereus), faces prolonged exposure to anthropogenic-induced stressors and assessment of chronic stress in wild populations is urgently warranted. One of the most effective ways to measure chronic stress is through analyzing the glucocorticoid hormone cortisol in hair or fur, as it supports physiological and behavioral responses. This laboratory validation study aims to test current techniques to validate an optimal hormone extraction method to be used as a non-invasive measure of cortisol in koala fur. It is recognized that using non-invasive techniques to measure stress hormones is preferred over traditional, invasive techniques due to their ideal practical and ethical standpoints. Additionally, it is comparatively easier to acquire fur from koalas than it is to acquire samples of their blood. This study used samples of koala fur acquired from the Adelaide Koala and Wildlife Hospital to run a number of hormone extraction techniques in an attempt to validate an optimal cortisol extraction method. Results showed that 100% methanol provided the most optimal solvent extraction compared to 100% ethanol or 100% isopropanol based on parallelism results. In conclusion, this method of cortisol extraction from koala fur provided a reliable non-invasive assay that could be used to study chronic stress in koalas.

Cortisol Measurement in Koala Phascolarctos cinereus Fur

We present a protocol to determine the optimal extraction solvent to measure cortisol from koala fur. The solvents used in this protocol are methanol, ethanol and isopropanol. Determining an optimal extraction solvent will aid in reliably measuring fur to determine the impact of chronic stress on koalas.

Optimal methods of hormone extraction used to measure stress in animals across sample types are not always the same. Australia&#39;s iconic marsupial ...

Identifying Amino Acid Overproducers Using Rare-Codon-Rich Markers

To satisfy the ever-growing market for amino acids, high-performance production strains are needed. The amino acid overproducers are conventionally identified by harnessing the competitions between amino acids and their analogs. However, this analog-based method is of low accuracy, and proper analogs for specific amino acids are limited. Here, we present an alternative strategy that enables an accurate, sensitive, and high-throughput screening of amino acid overproducers using rare-codon-rich markers. This strategy is inspired by the phenomenon of codon usage bias in protein translation, for which codons are categorized into common or rare ones based on their frequencies of occurrence in the coding DNA. The translation of rare codons depends on their corresponding rare transfer RNAs (tRNAs), which cannot be fully charged by the cognate amino acids under starvation. Theoretically, the rare tRNAs can be charged if there is a surplus of the amino acids after charging the synonymous common isoacceptors. Therefore, retarded translations caused by rare codons could be restored by feeding or intracellular overproductions of the corresponding amino acids. Under this assumption, a selection or screening system for identifying amino acid overproducers is established by replacing the common codons of the targeted amino acids with their synonymous rare alternatives in the antibiotic resistance genes or the genes encoding fluorescent or chromogenic proteins. We show that the protein expressions can be greatly hindered by the incorporation of rare codons and that the levels of proteins correlate positively with the amino acid concentrations. Using this system, overproducers of multiple amino acids can be readily screened out from mutation libraries. This rare-codon-based strategy only requires a single modified gene, and the host is less likely to escape the selection than in other methods. It offers an alternative approach for obtaining amino acid overproducers.

This study presents an alternative strategy to the conventional toxic analog-based method in identifying amino acid overproducers by using rare-codon-rich markers to achieve accuracy, sensitivity, and high-throughput simultaneously.

To satisfy the ever-growing market for amino acids, high-performance production strains are needed. The amino acid overproducers are conventionally ...

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 ...

Studies of Chaperone-Cochaperone Interactions using Homogenous Bead-Based Assay

Targeting the heat shock protein 90 (Hsp90)-cochaperone interactions provides the possibility to specifically regulate Hsp90-dependent intracellular processes. The conserved MEEVD pentapeptide at the C-terminus of Hsp90 is responsible for the interaction with the tetratricopeptide repeat (TPR) motif of co-chaperones. FK506-binding protein (FKBP) 51 and FKBP52 are two similar TPR-motif co-chaperones involved in steroid hormone-dependent diseases with different functions. Therefore, identifying molecules specifically blocking interactions between Hsp90 and FKBP51 or FKBP52 provides a promising therapeutic potential for several human diseases. Here, we describe the protocol for an amplified luminescent proximity homogenous assay to probe interactions between Hsp90 and its partner co-chaperones FKBP51 and FKBP52. First, we have purified the TPR motif-containing proteins FKBP51 and FKBP52 in glutathione S-transferase (GST)-tagged form. Using the glutathione-linked donor beads with GST-fused TPR-motif proteins and the acceptor beads coupled with a 10-mer C-terminal peptide of Hsp90, we have probed protein-protein interactions in a homogeneous environment. We have used this assay to screen small molecules to disrupt Hsp90-FKBP51 or Hsp90-FKBP52 interactions and identified potent and selective Hsp90-FKBP51 interaction inhibitors.

This protocol presents a technique for probing protein-protein interactions using glutathione-linked donor beads with GST-fused TPR-motif co-chaperones and acceptor beads coupled with an Hsp90-derived peptide. We have used this technique to screen small molecules to disrupt Hsp90-FKBP51 or Hsp90-FKBP52 interactions and identified potent and selective Hsp90-FKBP51 interaction inhibitors.

Targeting the heat shock protein 90 (Hsp90)-cochaperone interactions provides the possibility to specifically regulate Hsp90-dependent intracellular ...