Endogenous Protein Complexes
Endogenous Protein Complexes - Related Videos
05:35
Immunofluorescence Analysis of Endogenous and Exogenous Centromere-kinetochore Proteins
0 Views •
Cited by 4 •
2016
Here we report protocols to detect endogenous and exogenous centromere-kinetochore proteins in human cells and quantify these protein levels at centromeres-kinetochores by indirect immunofluorescent staining through the use of fixation (paraformaldehyde, acetone, or methanol fixation).
02:41
Protein Complex Assembly
0 Views •
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
0 Views •
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...
13:46
Immunoprecipitation-Based Techniques: Purification of Endogenous Proteins Using Agarose Beads
0 Views •
2023
Source: Susannah C. Shissler1, Tonya J. Webb1 1 Department of Microbiology and Immunology, University of Maryland, Baltimore, MD 21201 Immunoprecipitation (IP, also known as a 'pull-down' assay) is a widely used technique that has applications in a variety of fields. First conceived in 1984, it was refined in 1988 (1, 2). The fundamental goal of IP is purification and isolation of a specific protein using an antibody against that protein. The word "immuno" refers to the use of an antibody while...
05:13
Isolation of Proteins from Viral DNA-protein Complexes
0 Views •
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...
FAQs
Several interaction forces can stabilize these assemblies at the same time. Hydrogen bonds and electrostatic attractions help recognize compatible surfaces, while hydrophobic contacts contribute to association within the cellular environment. Because these interactions are often reversible, proteins can assemble and dissociate as conditions change, allowing complex formation to support regulated biochemical activity rather than permanent association.
Cofactors and post-translational modifications can determine whether compatible proteins associate or remain separate. They may alter recognition surfaces or otherwise affect the molecular conditions that favor assembly. Cellular location and protein concentration also matter, because proteins must occupy the same environment and reach suitable local concentrations for their interactions to occur efficiently.
Reversible association helps explain how a complex can respond to changing cellular conditions. Alterations in molecular concentration, location, cofactors, or post-translational modifications may shift the balance between assembled and unassembled forms. This behavior is important for interpreting measurements, since disrupting native conditions can change which interactions are detected and may obscure the complex's physiological activity.
Researchers examine assemblies formed inside cells rather than relying only on proteins produced through recombinant expression. Native complexes preserve the cellular context that influences association, including location, concentration, cofactors, and post-translational modifications. Comparing evidence from endogenous material with biochemical or structural analyses helps separate physiologically relevant interactions from associations created or altered during artificial protein production.
Co-immunoprecipitation, native electrophoresis, affinity purification, and structural analysis provide complementary ways to investigate these assemblies. Together, they can test whether proteins associate under native conditions, separate complexes without fully disrupting them, enrich interacting components, and examine structural organization. Using multiple approaches strengthens interpretation because each method addresses a different aspect of the interaction.
These studies connect protein structure with function and help map interaction networks within cells. They can clarify how complexes contribute to enzyme regulation and signaling, while also showing how disrupted associations may relate to disease research. The resulting information helps distinguish a protein's isolated properties from activities that depend on its native molecular partners.