Name: actin co-sedimentation assay; for the analysis of protein binding to f-actin
Uploaded: 2008-03-28T01:00:00
Description: Watch this Scientific Journal Video about Actin Co-Sedimentation Assay; for the Analysis of Protein Binding to F-Actin at JoVE.com

Thank you to Dr. Praveen Kumar in the Wittman lab at UCSF for the movie of actin in HaCAT cells.

1. Preparation of actin
The source of actin used in this assay was non-muscle human platelets (&beta;-actin) obtained from Cytoskeleton Inc. Stock aliquots at 10 mg/ml are kept in the -70&ordm;C freezer. For the assay, the actin is diluted to 0.4 mg/ml in a buffer containing 5 mM Tris pH 8, 0.2 mM CaCl2, 0.2 mM ATP and 0.5 mM DTT, centrifuged at 20,000g for 10 mins at 4&ordm;C. The supernatant, which is monomeric actin is ready to be polymerized. Actin polymerization is induced by the ...

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	<li>Senetar, M. A., Foster, S. J., McCann, R. O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intrasteric+inhibition+mediates+the+interaction+of+the+I/LWEQ+module+proteins+Talin1,+Talin2,+Hip1,+and+Hip12+with+actin.">Intrasteric inhibition mediates the interaction of the I/LWEQ module proteins Talin1, Talin2, Hip1, and Hip12 with actin.</a> Biochemistry. 14, 15418-15428 (2004).</li><li>Goldmann, W. H., Hess, D., Isenberg, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+effect+of+intact+talin+and+talin+tail+fragment+on+actin+filament+dynamics+and+structure+depends+on+pH+and+ionic+strength.">The effect of intact talin and talin tail fragment on actin filament dynamics and structure depends on pH and ionic strength.</a> Eur J Biochem. 260, 439-445 (1999).</li><li>Lee, H., Bellin, R. M., Walker, D. L., Patel, B., Powers, P., Liu, H., Garcia-Alvarez, B., de Pereda, J., Liddington, R. C., Volkmann, N., Hanein, D., Critchley, D. R., Robson, R. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+an+Actin-binding+Site+within+the+Talin+FERM+Domain.">Characterization of an Actin-binding Site within the Talin FERM Domain.</a> J Mol Biol. 22, 771-784 (2004).</li></ol>

Actin co-sedimentation is a simple in vitro assay to analyze specfic proteins binding to F-actin. In this video, we demonstrate one example of how a simple actin co-sedimentation can be carried out. We show how to prepare F-actin, prepare the protein to be tested and the procedure of actin co-sedimentation. A number of points should be considered when carrying out actin co-sedimentation assays. For instance, the buffer components for the incubation can vary depending on the protein to be tested and pH, temperature an...

actin co-sedimentation assay; for the analysis of protein binding to f-actin

The actin cytoskeleton within the cell is a network of actin filaments that allows the movement of cells and cellular processes, and that generates tension and helps maintains cellular shape.  Although the actin cytoskeleton is a rigid structure, it is a dynamic structure that is constantly remodeling.  A number of proteins can bind to the actin cytoskeleton.  The binding of a particular protein to F-actin is often desired to support cell biological observations or to further understand dynamic processes due to remodeling of the actin cytoskeleton. The actin co-sedimentation assay is an in vitro assay routinely used to analyze the binding of specific proteins or protein domains with F-actin.  The basic principles of the assay involve an incubation of the protein of interest (full length or domain of) with F-actin, ultracentrifugation step to pellet F-actin and analysis of the protein co-sedimenting with F-actin.  Actin co-sedimentation assays can be designed accordingly to measure actin binding affinities and in competition assays.

Watch this Scientific Journal Video about Actin Co-Sedimentation Assay; for the Analysis of Protein Binding to F-Actin at JoVE.com

Actin Co-Sedimentation Assay; for the Analysis of Protein Binding to F-Actin

Proteins bind to filamentous actin (F-actin) through distinct actin binding modules. In this video we demonstrate the procedure of actin co-sedimentation, which is an in vitro assay routinely used to analyze proteins or specific domains that bind F-actin.

The actin cytoskeleton within the cell is a network of actin filaments that allows the movement of cells and cellular processes, and that generates ...

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