Related Experiment Video
Updated: Jan 31, 2026
07:38
Measuring In Vitro ATPase Activity for Enzymatic Characterization
Published on: August 23, 2016
19.0K
The Enzymatic Activity of APOBE3G Multimers
Yangang Pan1, Karen Zagorski1, Luda S Shlyakhtenko2
1Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska, 68198-6025, USA.
Scientific Reports
|December 19, 2018
Summary
APOBEC3G (A3G) oligomerization is crucial for its antiviral function. This study reveals that A3G’s deaminase activity is maintained across various oligomeric states, including larger complexes.
Area of Science:
- Biochemistry
- Immunology
- Virology
Background:
- APOBEC3G (A3G) is a key enzyme in the innate immune system, functioning as a DNA deaminase.
- A3G's concentration-dependent oligomerization is essential for its antiviral activity, particularly in the roadblock model of reverse transcription.
- The deaminase activity of different A3G oligomeric forms remains poorly understood.
Purpose of the Study:
- To investigate the relationship between APOBEC3G oligomerization and its deaminase activity.
- To quantify the deaminase activity of individual oligomeric states of A3G within complexes.
- To elucidate the functional relevance of A3G oligomerization for its enzymatic function.
Main Methods:
- Atomic Force Microscopy (AFM) was used to visualize and characterize A3G-ssDNA complexes, determining yield and stoichiometry.
- Polymerase Chain Reaction (PCR) assays were employed to measure the deaminase activity of these complexes.
- Quantitative analysis was performed to correlate complex formation with enzymatic activity across different oligomeric states.
Main Results:
- A direct correlation was observed between the total yield of A3G-ssDNA complexes and their overall deaminase activity.
- The relative deaminase activity was calculated for monomer, dimer, and tetramer forms of A3G within complexes.
- Results indicate that A3G retains deaminase activity across monomeric, dimeric, tetrameric, and larger oligomeric forms.
Conclusions:
- Oligomerization does not diminish APOBEC3G's deaminase activity; rather, it is maintained across various forms.
- Both low-order and higher-order oligomers of A3G contribute to its functional deaminase activity.
- These findings clarify the role of A3G oligomerization in its innate immune function and antiviral mechanisms.
Related Concept Videos
01:22Amplifying Signals via Enzymatic Cascade
18.5K
When a ligand binds to a cell-surface receptor, the receptor's intracellular domain changes shape, which may either activate its enzyme function or allow its binding to other molecules. The initial signal is amplified by most signal transduction pathways. This means that a single ligand molecule can activate multiple molecules of a downstream target. Proteins that relay a signal are most commonly phosphorylated at one or more sites, activating or inactivating the protein. Kinases catalyze...
18.5K
02:04Co-activators and Co-repressors
8.6K
Gene transcription is regulated by the synergistic action of several proteins that form a complex at a gene regulatory site. This is observed in eukaryotes, where the regulation of gene expression is a complex process. Regulatory proteins in eukaryotes can broadly be classified into two types – regulators that bind directly to specific DNA sequences and co-regulators that associate with regulatory proteins but cannot directly bind to the DNA. These co-regulators are further divided into...
8.6K
02:26tRNA Activation
22.9K
Aminoacyl-tRNA synthetases are present in both eukaryotes and bacteria. Though eukaryotes have 20 different aminoacyl-tRNA synthetases to couple to 20 amino acids, many bacteria do not have genes for all of these aminoacyl-tRNA synthetases. Despite this, they still use all 20 amino acids to synthesize their proteins. For instance, some bacteria do not have the gene encoding the enzyme that couples glutamine with its partner tRNA. In these organisms, one enzyme adds glutamic acid to all of the...
22.9K
01:26Activation Energy
86.6K
Activation energy is the minimum amount of energy necessary for a chemical reaction to move forward. The higher the activation energy, the slower the rate of the reaction. However, adding heat to the reaction will increase the rate, since it causes molecules to move faster and increase the likelihood that molecules will collide. The collision and breaking of bonds represents the uphill phase of a reaction and generates the transition state. The transition state is an unstable high-energy state...
86.6K
02:42Eukaryotic Transcription Activators
12.8K
Transcription activators are proteins that promote the transcription of genes from DNA to RNA. In most cases, these proteins contain two separate domains ‒ a domain that binds to DNA and a domain for activating transcription; however, in some cases, a single domain is responsible for both binding and activation of transcription, as seen in the glucocorticoid receptor and MyoD.
The binding domains are capable of recognizing and interacting with regulatory sequences on the DNA. These...
The binding domains are capable of recognizing and interacting with regulatory sequences on the DNA. These...
12.8K
01:55Secondary Active Transport
137.8K
One example of how cells use the energy contained in electrochemical gradients is demonstrated by glucose transport into cells. The ion vital to this process is sodium (Na+), which is typically present in higher concentrations extracellularly than in the cytosol. Such a concentration difference is due, in part, to the action of an enzyme “pump” embedded in the cellular membrane that actively expels Na+ from a cell. Importantly, as this pump contributes to the high concentration of...
137.8K