Related Experiment Video
Updated: Aug 8, 2026
Identification of protein complexes with quantitative proteomics in S. cerevisiae
Published on: March 4, 2009
Actin in the ciliated protozoan Climacostomum virens: purification by DNAse I affinity chromatography,
1Department of Zoology and Animal Biology, Sciences III, Geneva, Switzerland.
Insights
Researchers identified a unique 43 kD actin protein in Climacostomum using the JLA20 antibody. This novel actin isoform binds DNAse I, purifies via affinity chromatography, and polymerizes into filaments.
Area of Science:
- Cell Biology
- Biochemistry
- Protein Characterization
Background:
- Actin proteins are essential cytoskeletal components found across eukaryotes.
- Characterizing novel actin isoforms is crucial for understanding cellular structure and function.
Purpose of the Study:
- To identify and characterize a specific actin protein in Climacostomum using the anti-actin monoclonal antibody JLA20.
- To determine the biochemical properties and polymerization capabilities of this novel actin.
Main Methods:
- Western blotting with monoclonal antibodies (mab) JLA20, anti-alpha-smooth muscle actin, and anti-alpha-sarcomeric actin.
- DNAse I binding assays and affinity chromatography for protein purification.
- Two-dimensional gel electrophoresis to analyze protein charge heterogeneity.
- Electron microscopy for visualizing actin filament polymerization.
Main Results:
- The JLA20 mab specifically labeled a 43 kD protein in Climacostomum extracts, distinct from mammalian actin isoforms.
- This protein exhibited DNAse I binding and was successfully purified via DNAse I affinity chromatography.
- Two-dimensional gel electrophoresis showed three basic spots for Climacostomum actin, differing from mammalian actins.
- Purified actin polymerized into filaments upon KCl addition, confirmed by electron microscopy.
Conclusions:
- Climacostomum possesses a unique actin isoform recognized by mab JLA20.
- This actin isoform shares functional properties with known actins, including DNAse I binding and polymerization.
- The distinct electrophoretic properties suggest significant divergence from mammalian actin isoforms.
Abstract:
The anti-actin monoclonal antibody (mab) JLA20 (Lin: Proc. Natl. Acad. Sci. U.S.A. 78:2335-2339, 1981) labels a 43 kD protein on Western blots of Climacostomum cell extracts; this protein does not react with an anti-alpha-smooth muscle actin mab (Skalli et al.: J. Cell Biol. 103:2787-2796, 1986) nor with an anti-alpha-sarcomeric actin mab (Skalli et al.: Am. J. Pathol. 130:515-531, 1988). This protein binds to DNAse I and can be purified by DNAse I affinity chromatography. The affinity-purified actin also reacts with mab JLA20. Two-dimensional gel analysis reveals that Climacostomum actin focuses as three spots which are more basic than the mammalian actin isoforms. After addition of KCl, the affinity-purified actin polymerizes into filaments as shown by electron microscopy after negative staining.
