Name: nitrogen cavitation and differential centrifugation allows for monitoring the distribution of peripheral membrane proteins in cultured cells
Uploaded: 2017-08-18T14:00:00
Description: Watch this Scientific Journal Video about Nitrogen Cavitation and Differential Centrifugation Allows for Monitoring the Distribution of Peripheral Membrane Proteins in Cultured Cells at JoVE.com

This work was funded by GM055279, CA116034 and CA163489.

1. Buffer and Equipment Preparations
<ol>
	<li>Chill 45 mL cell disruption bombs, 15 mL tubes, and ultracentrifugation tubes at 4 &#176;C.</li>
	<li>Prepare and chill 25 mL of homogenization buffer per 2 x 107 cells at 4 &#176;C. Add one protease inhibitor tablet just before use. 
	NOTE: Homogenization buffers typically contain KCl rather than NaCl to better reflect intracellular salt composition. Homogenization buffer used in this protocol consists of 10 mM HEPES at pH 7.4, 10 mM KCl and 1.5 mM MgCl<su...

<ol>
	<li>Miyawaki, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Proteins+on+the+move:+insights+gained+from+fluorescent+protein+technologies.">Proteins on the move: insights gained from fluorescent protein technologies.</a> Nat Rev Mol Cell Biol. 12 (10), 656-668 (2011).</li><li>Bunger, S., Roblick, U. J., Habermann, J. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+of+five+commercial+extraction+kits+for+subsequent+membrane+protein+profiling.">Comparison of five commercial extraction kits for subsequent membrane protein profiling.</a> Cytotechnology. 61 (3), 153-159 (2009).</li><li>Simpson, R. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Disruption+of+cultured+cells+by+nitrogen+cavitation.">Disruption of cultured cells by nitrogen cavitation.</a> Cold Spring Harb Protoc. (11), (2010).</li><li>Klempner, M. S., Mikkelsen, R. B., Corfman, D. H., Andre-Schwartz, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neutrophil+plasma+membranes.+I.+High-yield+purification+of+human+neutrophil+plasma+membrane+vesicles+by+nitrogen+cavitation+and+differential+centrifugation.">Neutrophil plasma membranes. I. High-yield purification of human neutrophil plasma membrane vesicles by nitrogen cavitation and differential centrifugation.</a> J Cell Biol. 86 (1), 21-28 (1980).</li><li>Philips, M. R., 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=Low+molecular+weight+GTP-binding+proteins+in+human+neutrophil+granule+membranes.">Low molecular weight GTP-binding proteins in human neutrophil granule membranes.</a> Journal of Biological Chemistry. 266, 1289-1298 (1991).</li><li>Wallach, D. F., Soderberg, J., Bricker, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+phospholipides+of+Ehrlich+ascites+carcinoma+cells:+composition+and+intracellular+distribution.">The phospholipides of Ehrlich ascites carcinoma cells: composition and intracellular distribution.</a> Cancer Res. 20, 397-402 (1960).</li><li>Hunter, M. J., Commerford, S. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pressure+homogenization+of+mammalian+tissues.">Pressure homogenization of mammalian tissues.</a> Biochim Biophys Acta. 47, 580-586 (1961).</li><li>Wallach, D. F., Kamat, V. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Plasma+and+Cytoplasmic+Membrane+Fragments+from+Ehrlich+Ascites+Carcinoma.">Plasma and Cytoplasmic Membrane Fragments from Ehrlich Ascites Carcinoma.</a> Proc Natl Acad Sci U S A. 52, 721-728 (1964).</li><li>Birckbichler, P. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preperation+of+plasma+membrane+vesicles+by+nitrogen+cavitation.">Preperation of plasma membrane vesicles by nitrogen cavitation.</a> TCA manual / Tissue Culture Association. 3 (3), 653-654 (1977).</li><li>Brock, T. G., Paine, R., Peters-Golden, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Localization+of+5-lipoxygenase+to+the+nucleus+of+unstimulated+rat+basophilic+leukemia+cells.">Localization of 5-lipoxygenase to the nucleus of unstimulated rat basophilic leukemia cells.</a> J Biol Chem. 269 (35), 22059-22066 (1994).</li><li>Dowben, R. M., Gaffey, A., Lynch, P. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+of+liver+and+muscle+polyribosomes+in+high+yield+after+cell+disruption+by+nitrogen+cavitation.">Isolation of liver and muscle polyribosomes in high yield after cell disruption by nitrogen cavitation.</a> FEBS Letters. 2 (1), (1968).</li><li>Dai, Q., 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=Mammalian+prenylcysteine+carboxyl+methyltransferase+is+in+the+endoplasmic+reticulum.">Mammalian prenylcysteine carboxyl methyltransferase is in the endoplasmic reticulum.</a> J Biol Chem. 273 (24), 15030-15034 (1998).</li><li>Wynne, J. P., 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=Rap1-interacting+adapter+molecule+(RIAM)+associates+with+the+plasma+membrane+via+a+proximity+detector.">Rap1-interacting adapter molecule (RIAM) associates with the plasma membrane via a proximity detector.</a> J Cell Biol. , (2012).</li><li>Zhou, M., 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=VPS35+binds+farnesylated+N-Ras+in+the+cytosol+to+regulate+N-Ras+trafficking.">VPS35 binds farnesylated N-Ras in the cytosol to regulate N-Ras trafficking.</a> J Cell Biol. 214 (4), 445-458 (2016).</li><li>Sim, D. S., Dilks, J. R., Flaumenhaft, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Platelets+possess+and+require+an+active+protein+palmitoylation+pathway+for+agonist-mediated+activation+and+in+vivo+thrombus+formation.">Platelets possess and require an active protein palmitoylation pathway for agonist-mediated activation and in vivo thrombus formation.</a> Arterioscler Thromb Vasc Biol. 27 (6), 1478-1485 (2007).</li><li>Pace, P. E., Peskin, A. V., Han, M. H., Hampton, M. B., Winterbourn, C. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hyperoxidized+peroxiredoxin+2+interacts+with+the+protein+disulfide-+isomerase+ERp46.">Hyperoxidized peroxiredoxin 2 interacts with the protein disulfide- isomerase ERp46.</a> Biochem J. 453 (3), 475-485 (2013).</li><li>Annis, M. G., 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=Endoplasmic+reticulum+localized+Bcl-2+prevents+apoptosis+when+redistribution+of+cytochrome+c+is+a+late+event.">Endoplasmic reticulum localized Bcl-2 prevents apoptosis when redistribution of cytochrome c is a late event.</a> Oncogene. 20 (16), 1939-1952 (2001).</li><li>Berkowitz, S. A., Wolff, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intrinsic+calcium+sensitivity+of+tubulin+polymerization.+The+contributions+of+temperature,+tubulin+concentration,+and+associated+proteins.">Intrinsic calcium sensitivity of tubulin polymerization. The contributions of temperature, tubulin concentration, and associated proteins.</a> J Biol Chem. 256 (21), 11216-11223 (1981).</li></ol>

The advantages of nitrogen cavitation over other methods of mechanical disruption are manifold. Perhaps the most significant benefit is its ability to gently yet efficiently homogenize specimens. The physical principles of decompression cools samples instead of generating local heating damage like ultrasonic and friction/shearing based techniques. Cavitation is also extremely efficient at disrupting the plasma membrane. Because nitrogen bubbles are generated within each individual cell upon decompression, the cavitation ...

Cellular proteins can be divided into two classes: those that are associated with membranes and those that are not. Non-membrane associated proteins are found in the cytosol, nucleoplasm and lumina of organelles such as the endoplasmic reticulum (ER). There are two classes of membrane-associated proteins, integral and peripheral. Integral membrane proteins are also known as transmembrane proteins because one or more segments of the polypeptide chain spans the membrane, typically as an &#945;-helix composed of hydrophobic amino acids. Transmembrane proteins are co-translationally inserted into membranes in the course of their biosynthesis and remain so configured until they are catabolized. Peripheral membrane proteins are secondarily driven to membranes, usually as a consequence of post-translational modification with hydrophobic molecules such as lipids. In contrast to integral membrane proteins, the association of peripheral membrane proteins with cellular membranes is reversible and can be regulated. Many peripheral membrane proteins function in signaling pathways, and regulated association with membranes is one mechanism for activating or inhibiting a pathway. One example of a signaling molecule that is a peripheral membrane protein is the small GTPase, RAS. After a series of post-translational modifications that include modification with a farnesyl lipid, the modified C-terminus of a mature RAS protein inserts into the cytoplasmic leaflet of the cellular membrane. Specifically, the plasma membrane is where the RAS engages its downstream effector RAF1. To prevent constitutive activation of mitogen-activated protein kinase (MAPK) pathway, multiple levels of control of RAS are in place. Besides rendering RAS inactive by hydrolyzing GTP into GDP, active RAS also can be released from the plasma membrane by modifications or interactions with solubilizing factors to inhibit signaling. Although fluorescent live imaging affords cell biologists the opportunity to observe the subcellular localization of fluorescent protein-tagged peripheral membrane proteins1, there remains a critical need to evaluate membrane association of endogenous proteins semi-quantitatively with simple biochemical approaches.
The proper biochemical evaluation of protein partitioning between membrane and soluble fractions is critically dependent on two factors: cellular homogenization and efficient separation of membrane and soluble fractions. Although some protocols, including the most widely used commercialized kits, depend on detergent-based cell homogenization, these methods can obfuscate analysis by extracting membrane proteins into the soluble phase2. Accordingly, non-detergent based, mechanical methods of cell disruption provide cleaner results. There are several methods of mechanical disruption of cells grown in culture or harvested from blood or organs. These include Dounce homogenization, fine needle disruption, ball-bearing homogenization, sonication and nitrogen cavitation. Here we evaluate nitrogen cavitation and compare it to other methods. Nitrogen cavitation relies on nitrogen that is dissolved in the cytoplasm of the cells under high pressure. After equilibration, the cell suspension is abruptly exposed to atmospheric pressure such that nitrogen bubbles are formed in the cytoplasm that tear open the cell as a consequence of their effervescence. If the pressure is sufficiently high, nitrogen effervescence can disrupt the nucleus3 and membrane bound organelles like lysosomes4. However, if the pressure is kept low enough, the decompression will disrupt the plasma membrane and ER but not other organelles, thereby spilling both cytosol and intact cytoplasmic organelles into the homogenate that is designated the cavitate5. For this reason, nitrogen cavitation is the method of choice for isolating organelles like lysosomes and mitochondria.
However, it is also an excellent way of preparing a homogenate that can be easily separated into membrane and soluble fractions. The pressure vessel (henceforth called &#34;the bomb&#34;) used during cavitation consists of a thick stainless steel casing that withstands high pressure, with an inlet for delivery of the nitrogen gas from a tank and an outlet port with an adjustable discharge valve.
Nitrogen cavitation has been used for cell homogenization since the 1960s6. In 1961, Hunter and Commerfold7 established nitrogen cavitation as a viable option for mammalian tissue disruption. Since then, researchers have adapted the technique to various cells and tissues with success, and nitrogen cavitation has become a staple in multiple applications, including membrane preparation8,9, nuclei and organelle preparation10,11, and labile biochemical extraction. Currently, cell biologists more often employ other methods of cell homogenization because the benefits of nitrogen homogenization have not been widely advertised, nitrogen bombs are expensive and there is a misconception that a relatively large number of cells is required. Protocols for nitrogen cavitation to achieve cell-free homogenates with intact nuclei have not been published, and in most published evaluations volumes of 20 mL of cell suspension were used. To adapt this classic technique to suit current requirements of working with small-scale samples, we present a modified protocol of nitrogen cavitation specifically designed for cultured cells. After nitrogen cavitation, the homogenate is separated into soluble (S) and membrane (P) fractions by differential centrifugation, first with a low-speed spin to remove nuclei and unbroken cells, and then with a high-speed spin (&#62;100,000 x g) to separate membranes from the soluble fraction. We analyze the efficiency of the separation with immunoblots and compare nitrogen cavitation with other mechanical disruption techniques. We also investigate the osmotic effect of homogenization buffer during nitrogen cavitation.

<table border="0" cellpadding="0" cellspacing="0" width="1015">
	<tbody>
		<tr height="33">
			<td height="33" style="height:33px;width:393px;">Cell Disruption Vessel (45 mL)</td>
			<td style="width:181px;">Parr Instrument</td>
			<td style="width:145px;">4639</td>
			<td style="width:296px;">Nitrogen cavitation Bomb</td>
		</tr>
		<tr height="33">
			<td height="33" style="height:33px;width:393px;">Dounce homogenizer (2 mL)</td>
			<td style="width:181px;">Kontes</td>
			<td style="width:145px;">885300-0002</td>
			<td style="width:296px;">Dounce pestle and tube</td>
		</tr>
		<tr height="33">
			<td height="33" style="height:33px;width:393px;">U-100 Insulin Syringe 28G&#189;</td>
			<td style="width:181px;">Becton Dickinson</td>
			<td style="width:145px;">329461</td>
			<td style="width:296px;">Needle</td>
		</tr>
		<tr height="33">
			<td height="33" style="height:33px;width:393px;">Atg12 antibody</td>
			<td style="width:181px;">Santa Cruz</td>
			<td style="width:145px;">271688</td>
			<td style="width:296px;">Mouse antibody, use at 1:1000 dilution</td>
		</tr>
		<tr height="33">
			<td height="33" style="height:33px;width:393px;">&#946;-actin antibody</td>
			<td style="width:181px;">Santa Cruz</td>
			<td style="width:145px;">47778</td>
			<td style="width:296px;">Mouse antibody, use at 1:1000 dilution</td>
		</tr>
		<tr height="33">
			<td height="33" style="height:33px;width:393px;">&#946;-tubulin antibody</td>
			<td style="width:181px;">DSHB</td>
			<td style="width:145px;">E7-s</td>
			<td style="width:296px;">Mouse antibody, use at 1:5000 dilution</td>
		</tr>
		<tr height="33">
			<td height="33" style="height:33px;width:393px;">Calnexin antibody</td>
			<td style="width:181px;">Santa Cruz</td>
			<td style="width:145px;">23954</td>
			<td style="width:296px;">Mouse antibody, use at 1:1000 dilution</td>
		</tr>
		<tr height="33">
			<td height="33" style="height:33px;width:393px;">Calregulin antibody</td>
			<td style="width:181px;">Santa Cruz</td>
			<td style="width:145px;">373863</td>
			<td style="width:296px;">Mouse antibody, use at 1:1000 dilution</td>
		</tr>
		<tr height="33">
			<td height="33" style="height:33px;width:393px;">Catalase antibody</td>
			<td style="width:181px;">Santa Cruz</td>
			<td style="width:145px;">271803</td>
			<td style="width:296px;">Mouse antibody, use at 1:1000 dilution</td>
		</tr>
		<tr height="33">
			<td height="33" style="height:33px;width:393px;">CIMPR antibody</td>
			<td style="width:181px;">Abcam</td>
			<td style="width:145px;">124767</td>
			<td style="width:296px;">Rabbit antibody, use at 1:1000 dilution</td>
		</tr>
		<tr height="33">
			<td height="33" style="height:33px;width:393px;">EEA1 antibody</td>
			<td style="width:181px;">Santa Cruz</td>
			<td style="width:145px;">137130</td>
			<td style="width:296px;">Mouse antibody, use at 1:1000 dilution</td>
		</tr>
		<tr height="33">
			<td height="33" style="height:33px;width:393px;">EGFR antibody</td>
			<td style="width:181px;">Santa Cruz</td>
			<td style="width:145px;">373746</td>
			<td style="width:296px;">Mouse antibody, use at 1:1000 dilution</td>
		</tr>
		<tr height="33">
			<td height="33" style="height:33px;width:393px;">F0-ATPase antibody</td>
			<td style="width:181px;">Santa Cruz</td>
			<td style="width:145px;">514419</td>
			<td style="width:296px;">Mouse antibody, use at 1:1000 dilution</td>
		</tr>
		<tr height="33">
			<td height="33" style="height:33px;width:393px;">F1-ATPase antibody</td>
			<td style="width:181px;">Santa Cruz</td>
			<td style="width:145px;">55597</td>
			<td style="width:296px;">Mouse antibody, use at 1:1000 dilution</td>
		</tr>
		<tr height="33">
			<td height="33" style="height:33px;width:393px;">Fibrillarin antibody</td>
			<td style="width:181px;">Santa Cruz</td>
			<td style="width:145px;">374022</td>
			<td style="width:296px;">Mouse antibody, use at 1:200 dilution</td>
		</tr>
		<tr height="33">
			<td height="33" style="height:33px;width:393px;">Golgin 97 antibody</td>
			<td style="width:181px;">Santa Cruz</td>
			<td style="width:145px;">59820</td>
			<td style="width:296px;">Mouse antibody, use at 1:1000 dilution</td>
		</tr>
		<tr height="33">
			<td height="33" style="height:33px;width:393px;">HDAC1 antibody</td>
			<td style="width:181px;">Santa Cruz</td>
			<td style="width:145px;">81598</td>
			<td style="width:296px;">Mouse antibody, use at 1:1000 dilution</td>
		</tr>
		<tr height="33">
			<td height="33" style="height:33px;width:393px;">Hexokinase 1 antibody</td>
			<td style="width:181px;">Cell Signaling Technology</td>
			<td style="width:145px;">2024S</td>
			<td style="width:296px;">Rabbit antibody, use at 1:1000 dilution</td>
		</tr>
		<tr height="33">
			<td height="33" style="height:33px;width:393px;">Lamin A/C antibody</td>
			<td style="width:181px;">Santa Cruz</td>
			<td style="width:145px;">376248</td>
			<td style="width:296px;">Mouse antibody, use at 1:1000 dilution</td>
		</tr>
		<tr height="33">
			<td height="33" style="height:33px;width:393px;">LAMP1 antibody</td>
			<td style="width:181px;">DSHB</td>
			<td style="width:145px;">H4A3-c</td>
			<td style="width:296px;">Mouse antibody, use at 1:1000 dilution</td>
		</tr>
		<tr height="33">
			<td height="33" style="height:33px;width:393px;">Na+/K+ ATPase antibody</td>
			<td style="width:181px;">Santa Cruz</td>
			<td style="width:145px;">48345</td>
			<td style="width:296px;">Mouse antibody, use at 1:1000 dilution</td>
		</tr>
		<tr height="33">
			<td height="33" style="height:33px;width:393px;">Rab7 antibody</td>
			<td style="width:181px;">Abcam</td>
			<td style="width:145px;">137029</td>
			<td style="width:296px;">Rabbit antibody, use at 1:1000 dilution</td>
		</tr>
		<tr height="33">
			<td height="33" style="height:33px;width:393px;">Rab9 antibody</td>
			<td style="width:181px;">Thermo</td>
			<td style="width:145px;">MA3-067</td>
			<td style="width:296px;">Mouse antibody, use at 1:1000 dilution</td>
		</tr>
		<tr height="33">
			<td height="33" style="height:33px;width:393px;">RCAS1 antibody</td>
			<td style="width:181px;">Santa Cruz</td>
			<td style="width:145px;">398052</td>
			<td style="width:296px;">Mouse antibody, use at 1:1000 dilution</td>
		</tr>
		<tr height="33">
			<td height="33" style="height:33px;width:393px;">RhoGDI antibody</td>
			<td style="width:181px;">Santa Cruz</td>
			<td style="width:145px;">360</td>
			<td style="width:296px;">Rabbit antibody, use at 1:3000 dilution</td>
		</tr>
		<tr height="33">
			<td height="33" style="height:33px;width:393px;">Ribosomal protein S6 antibody</td>
			<td style="width:181px;">Santa Cruz</td>
			<td style="width:145px;">74459</td>
			<td style="width:296px;">Mouse antibody, use at 1:1000 dilution</td>
		</tr>
		<tr height="33">
			<td height="33" style="height:33px;width:393px;">Sec61a antibody</td>
			<td style="width:181px;">Santa Cruz</td>
			<td style="width:145px;">12322</td>
			<td style="width:296px;">Goat antibody, use at 1:1000 dilution</td>
		</tr>
		<tr height="33">
			<td height="33" style="height:33px;width:393px;">Thickwall Polycarbonate ultracentrifuge tube</td>
			<td style="width:181px;">Beckman Coulter</td>
			<td style="width:145px;">349622</td>
			<td style="width:296px;">Sample tube for ultracentrifugation</td>
		</tr>
		<tr height="33">
			<td height="33" style="height:33px;width:393px;">TLK-100.3 rotor</td>
			<td style="width:181px;">Beckman Coulter</td>
			<td style="width:145px;">349481</td>
			<td style="width:296px;">rotor for ultracentrifugation</td>
		</tr>
		<tr height="33">
			<td height="33" style="height:33px;width:393px;">Optima MAX High-Capacity Personal Ultracentrifuge</td>
			<td style="width:181px;">Beckman Coulter</td>
			<td style="width:145px;">364300</td>
			<td style="width:296px;">ultracentrifuge</td>
		</tr>
		<tr height="33">
			<td height="33" style="height:33px;width:393px;">cOmplete protease inhibitor cocktail tablets</td>
			<td>Roche</td>
			<td>11697498001</td>
			<td>protease inhibitors</td>
		</tr>
		<tr height="33">
			<td height="33" style="height:33px;">Cell Scrapers with 25cm Handle and 3.0cm Blade</td>
			<td>Corning</td>
			<td>353089</td>
			<td>large cell scraper</td>
		</tr>
		<tr height="33">
			<td height="33" style="height:33px;">Magnetic Stir Bar</td>
			<td>Fisher Scientific</td>
			<td>14-513-57SIX</td>
			<td>micro stir bar</td>
		</tr>
		<tr height="33">
			<td height="33" style="height:33px;">Ceramic-Top Magnetic Stirrer</td>
			<td>Fisher Scientific</td>
			<td>S504501AS</td>
			<td>magnetic stirrer</td>
		</tr>
	</tbody>
</table>

nitrogen cavitation and differential centrifugation allows for monitoring the distribution of peripheral membrane proteins in cultured cells

Cultured cells are useful for studying the subcellular distribution of proteins, including peripheral membrane proteins. Genetically encoded fluorescently tagged proteins have revolutionized the study of subcellular protein distribution. However, it is difficult to quantify the distribution with fluorescent microscopy, especially when proteins are partially cytosolic. Moreover, it is often important to study endogenous proteins. Biochemical assays such as immunoblots remain the gold standard for quantification of protein distribution after subcellular fractionation. Although there are commercial kits that aim to isolate cytosolic or certain membrane fractions, most of these kits are based on extraction with detergents, which may be unsuitable for studying peripheral membrane proteins that are easily extracted from membranes. Here we present a detergent-free protocol for cellular homogenization by nitrogen cavitation and subsequent separation of cytosolic and membrane-bound proteins by ultracentrifugation. We confirm the separation of subcellular organelles in soluble and pellet fractions across different cell types, and compare protein extraction among several common non-detergent-based mechanical homogenization methods. Among several advantages of nitrogen cavitation is the superior efficiency of cellular disruption with minimal physical and chemical damage to delicate organelles. Combined with ultracentrifugation, nitrogen cavitation is an excellent method to examine the shift of peripheral membrane proteins between cytosolic and membrane fractions.

Figure 2 shows the partitioning of cellular proteins from PNS into either the soluble cytosolic fraction (S) or membrane pellet fraction (P). We examined three representative cell lines from different cell types: HEK-293 (epithelial), NIH-3T3 (fibroblast), and Jurkat (lymphocyte). Rho Guanine Dissociation Inhibitor (RhoGDI) and cation-independent mannose-6-phosphate receptor (CIMPR) were used as positive controls for cytosolic and membrane fractions, respecti...

Watch this Scientific Journal Video about Nitrogen Cavitation and Differential Centrifugation Allows for Monitoring the Distribution of Peripheral Membrane Proteins in Cultured Cells at JoVE.com

Nitrogen Cavitation and Differential Centrifugation Allows for Monitoring the Distribution of Peripheral Membrane Proteins in Cultured Cells

Here we present protocols for detergent-free homogenization of cultured mammalian cells based on nitrogen cavitation and subsequent separation of cytosolic and membrane-bound proteins by ultracentrifugation. This method is ideal for monitoring the partitioning of peripheral membrane proteins between soluble and membrane fractions.

Cultured cells are useful for studying the subcellular distribution of proteins, including peripheral membrane proteins. Genetically encoded fluorescently ...

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JoVE Journal

Biochemistry

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

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 ...

Preparation of Giant Vesicles Encapsulating Microspheres by Centrifugation of a Water-in-oil Emulsion

The constructive biology and the synthetic biology approach to creating artificial life involve the bottom-up assembly of biological or nonbiological ...

Purification of Biotinylated Cell Surface Proteins from Rhipicephalus microplus Epithelial Gut Cells

Purification of Biotinylated Cell Surface Proteins from Rhipicephalus microplus Epithelial Gut Cells

Rhipicephalus microplus &#8211; the cattle tick &#8211; is the most significant ectoparasite in terms of economic impact on livestock as a vector of ...

Dissipative Microgravimetry to Study the Binding Dynamics of the Phospholipid Binding Protein Annexin A2 to Solid-supported Lipid Bilayers Using a Quartz Resonator

The dissipative quartz crystal microbalance technique is a simple and label-free approach to measure simultaneously the mass uptake and viscoelastic ...

A Fluorescence Fluctuation Spectroscopy Assay of Protein-Protein Interactions at Cell-Cell Contacts

A variety of biological processes involves cell-cell interactions, typically mediated by proteins that interact at the interface between neighboring ...

Cell Fractionation of U937 Cells in the Absence of High-speed Centrifugation

In this protocol we detail a method to obtain subcellular fractions of U937 cells without the use of ultracentrifugation or indiscriminate detergents. ...

Measuring Nucleotide Binding to Intact, Functional Membrane Proteins in Real Time

We have developed a method to measure binding of adenine nucleotides to intact, functional transmembrane receptors in a cellular or membrane environment. ...

Transverse Sectioning of Mature Rice (Oryza sativa L.) Kernels for Scanning Electron Microscopy Imaging Using Pipette Tips as Immobilization Support

Transverse Sectioning of Mature Rice Oryza sativa L. Kernels for Scanning Electron Microscopy Imaging Using Pipette Tips as Immobilization Support

Starch granules (SGs) exhibit different morphologies depending on the plant species, especially in the endosperm of the Poaceae family. Endosperm ...

Cell-Free Production of Proteoliposomes for Functional Analysis and Antibody Development Targeting Membrane Proteins

Membrane proteins play essential roles in a variety of cellular processes and perform vital functions. Membrane proteins are medically important in drug ...

Identifying the Binding Proteins of Small Ligands with the Differential Radial Capillary Action of Ligand Assay (DRaCALA)

Identifying the Binding Proteins of Small Ligands with the Differential Radial Capillary Action of Ligand Assay DRaCALA

The past decade has seen tremendous progress in the understanding of small signaling molecules in bacterial physiology. In particular, the target proteins ...