Protein Complex Characterization
Protein Complex Characterization - Related Videos
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...
08:55
Characterization of Multi-subunit Protein Complexes of Human MxA Using Non-denaturing Polyacrylamide Gel-electrophoresis
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Cited by 3 •
2016
This article describes a simple and rapid protocol to evaluate the oligomeric state of the dynamin-like GTPase MxA protein from lysates of human cells using a combination of non-denaturing PAGE with western blot analysis.
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...
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
Preserving native conditions helps researchers examine assemblies in a state that remains relevant to their biological function. Disrupting those conditions can alter which proteins stay associated, making an observed interaction difficult to distinguish from an artifact. Native handling therefore supports more credible measurements of complex composition and organization before downstream analysis.
These methods provide complementary ways to isolate or separate complexes while preserving their assembled state. Using affinity purification, native electrophoresis, or size-exclusion chromatography can expose different features of the same system, such as whether an assembly can be captured selectively or separated according to its native behavior. Method selection therefore shapes downstream interpretation.
Mass spectrometry identifies the protein components present in an isolated complex, converting a separation step into a molecular inventory. That inventory can be compared with interaction-assay and structural evidence to distinguish likely members from broader association patterns. In practice, it helps connect detected composition with questions about assembly, regulation, and function.
Interaction assays can test how proteins associate, while structural analyses add information about arrangement and physical changes. Together, they can clarify stoichiometry, meaning the number or proportion of components in an assembly, identify binding sites, and reveal conformational changes. These measurements move characterization beyond membership toward a mechanistic explanation of complex function.
A practical workflow begins by maintaining complexes under native conditions, followed by isolation or separation with an appropriate method. Mass spectrometry can then identify associated proteins, while interaction assays and structural analyses examine organization and behavior. The resulting evidence should be interpreted together, because composition alone does not establish stoichiometry, binding sites, or conformational changes.
It links altered assembly with biological consequences, including changes in signaling, enzyme regulation, and cellular behavior. In disease-focused studies, the measurements can clarify mechanisms associated with abnormal complex organization and help identify therapeutic targets. The same evidence also supports validation of interaction networks, allowing proposed molecular relationships to be evaluated against measured complex composition and interactions.