Protein Complex Isolation
Protein Complex Isolation - Related Videos
05:13
Isolation of Proteins from Viral DNA-protein Complexes
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2026
Source: Dembowski, J. A., et al. Purification of Viral DNA for the Identification of Associated Viral and Cellular Proteins. J. Vis. Exp. (2017).This video demonstrates the isolation of protein–viral DNA complexes from cell nuclei using click chemistry and magnetic bead purification. The protocol involves labeling viral genomes with alkyne-modified nucleotides, biotinylation via a click reaction, and binding to streptavidin-coated magnetic beads. Following washing and heat elution, the purified...
08:51
An in vivo Crosslinking Approach to Isolate Protein Complexes From Drosophila Embryos
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Cited by 6 •
2014
Multi-component protein complexes play crucial roles during cellular function and development. Here we describe a method used to isolate native protein complexes from Drosophila embryos after in vivo crosslinking followed by purification of the crosslinked complexes for subsequent structure-function analysis.
02:41
Protein Complex Assembly
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2020
Proteins can form homomeric complexes with another unit of the same protein or heteromeric complexes with different types. Most protein complexes self-assemble spontaneously via ordered pathways, while some proteins need assembly factors that guide their proper assembly. Despite the crowded intracellular environment, proteins usually interact with their correct partners and form functional complexes. Many viruses self-assemble into a fully functional unit using the infected host cell to...
01:57
Protein Complexes with Interchangeable Parts
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2020
Groups of proteins may form a complex where each protein in this complex has a different role in the overall execution of the complex’s function. Often some of the proteins in the complex can be replaced by a closely related variant to give a complex that contains many of the same components yet is functionally distinct. The SCF ubiquitin ligase is a protein complex of five individual proteins. This complex attaches ubiquitin to other target proteins to mark them for degradation. In order to...
15:35
Analyzing Large Protein Complexes by Structural Mass Spectrometry
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Cited by 68 •
2010
Mass spectrometry has proven to be a valuable tool for analyzing large protein complexes. This method enables insights into the composition, stoichiometry and overall architecture of multi-subunit assemblies. Here, we describe, step-by-step, how to perform a structural mass spectrometry analysis, and characterize macromolecular structures.
FAQs
These conditions help preserve the weak, noncovalent forces that hold protein partners together. Low temperatures can reduce unwanted degradation, while suitable salt concentration and pH help maintain protein solubility and interaction stability. If conditions become too harsh or poorly matched to the sample, subunits may dissociate, reducing recovery of the native complex and altering subsequent structural or functional measurements.
Affinity purification and immunoprecipitation select complexes through a specific binding interaction, such as recognition by an affinity reagent or antibody. Size-exclusion chromatography separates material according to molecular size and can help distinguish complexes from smaller components. The choice therefore depends on whether the experiment prioritizes selective capture, antibody-based enrichment, or separation by size.
Complex recovery depends on preserving interactions throughout sample preparation and separation. Inadequate control of lysis conditions, temperature, salt, or pH can weaken associations or affect protein solubility. Because isolated material may no longer represent the original cellular state if interactions are disrupted, researchers interpret composition and activity results in light of how well native conditions were maintained.
A typical workflow begins with controlled cell lysis, followed by a separation step such as affinity purification, immunoprecipitation, or size-exclusion chromatography. The recovered material is then examined by electrophoresis, mass spectrometry, or activity assays. These analyses can reveal complex subunits, associated interaction partners, and whether the isolated assembly retains a measurable biological function.
The approach can clarify how proteins are organized within signaling pathways, enzyme systems, and gene-regulatory processes. Identifying associated subunits or partners may show which proteins act together and how cellular mechanisms are coordinated. Comparing isolated complexes can also support investigation of changes linked to disease, including altered composition or function that may point toward therapeutic targets.
Researchers can use the method to examine whether disease-associated samples contain protein complexes with different subunits, interaction partners, or activities. Electrophoresis and mass spectrometry help characterize composition, whereas activity assays assess functional consequences. These findings can connect molecular changes to disrupted cellular pathways and help identify complexes or interactions for further therapeutic investigation.