Related Experiment Video
Updated: Jul 2, 2026
09:45
In Vitro SUMOylation Assay to Study SUMO E3 Ligase Activity
Published on: January 29, 2018
Mel-18 interacts with RanGAP1 and inhibits its sumoylation
1Graduate Center for Toxicology, University of Kentucky, Lexington, KY 40536, USA.
Biochemical and Biophysical Research Communications
|August 19, 2008
Summary
The polycomb protein mel-18 acts as an anti-SUMO E3 factor, inhibiting sumoylation of HSF2 and now also RanGAP1. Its interaction with RanGAP1 increases during mitosis, decreasing RanGAP1 sumoylation.
Area of Science:
- Cell Biology
- Molecular Biology
- Protein Biochemistry
Background:
- The polycomb protein mel-18 was previously identified as an inhibitor of Heat Shock Factor 2 (HSF2) sumoylation.
- This function suggested mel-18 acts as an anti-SUMO E3 factor, but its other targets remained unknown.
Purpose of the Study:
- To identify additional protein targets regulated by mel-18's anti-SUMO E3 activity.
- To investigate the interaction between mel-18 and its targets during the cell cycle, particularly mitosis.
Main Methods:
- Co-immunoprecipitation assays to detect protein interactions.
- Western blotting to assess protein sumoylation levels.
- Analysis of protein interactions and sumoylation during different cell cycle stages.
Main Results:
- Mel-18 directly interacts with Ran (Regulator of chromosome condensation) GTPase Activating Protein 1 (RanGAP1) and inhibits its sumoylation.
- The inhibitory activity of mel-18 on RanGAP1 sumoylation does not depend on its RING domain.
- RanGAP1 sumoylation decreases during mitosis, coinciding with increased mel-18 and RanGAP1 interaction.
Conclusions:
- Mel-18 functions as an anti-SUMO E3 factor, regulating the sumoylation of both HSF2 and RanGAP1.
- The interaction and regulatory relationship between mel-18 and RanGAP1 is cell cycle-dependent, notably during mitosis.
- These findings expand the known targets of mel-18's sumoylation regulatory activity to include the crucial cellular protein RanGAP1.
Related Concept Videos
02:23Abnormal Proliferation
Under normal conditions, most adult cells remain in a non-proliferative state unless stimulated by internal or external factors to replace lost cells. Abnormal cell proliferation is a condition in which the cell's growth exceeds and is uncoordinated with normal cells. In such situations, cell division persists in the same excessive manner even after cessation of the stimuli, leading to persistent tumors. The tumor arises from the damaged cells that replicate to pass the damage to the daughter...
01:23Negative Regulator Molecules
Positive regulators allow a cell to advance through cell cycle checkpoints. Negative regulators have an equally important role as they terminate a cell’s progression through the cell cycle—or pause it—until the cell meets specific criteria.
02:04Covalently Linked Protein Regulators
Proteins can undergo many types of post-translational modifications, often in response to changes in their environment. These modifications play an important role in the function and stability of these proteins. Covalently linked molecules include functional groups, such as methyl, acetyl, and phosphate groups, and also small proteins, such as ubiquitin. There are around 200 different types of covalent regulators that have been identified.
These groups modify specific amino acids in a protein.
These groups modify specific amino acids in a protein.
01:19Interactions Between Signaling Pathways
Signaling cascades usually lack linearity. Multiple pathways interact and regulate one another, allowing cells to integrate and respond to diverse environmental stimuli.
Convergence and divergence, and cross-talk between signaling pathways
Two distinct signaling pathways can converge on a single functional unit, which may either be a single protein or a complex of proteins. The response is either functionally distinct or synergistic between the two pathways but different from the response...
Convergence and divergence, and cross-talk between signaling pathways
Two distinct signaling pathways can converge on a single functional unit, which may either be a single protein or a complex of proteins. The response is either functionally distinct or synergistic between the two pathways but different from the response...
01:52Eukaryotic Transcription Inhibitors
Certain biochemical processes, such as embryonic development and cell growth regulation, depend on the repression of specific genes. DNA binding proteins known as eukaryotic transcription inhibitors regulate the repression of gene expression in eukaryotes. The presence of these inhibitors at the required location and time in the cell is triggered by the presence of hormones and additional signals from other cells.
Eukaryotic transcription inhibitors usually contain two distinct domains, a DNA...
Eukaryotic transcription inhibitors usually contain two distinct domains, a DNA...
00:50Anaphase Promoting Complex
The stepwise destruction of specific proteins is necessary for the progression and completion of the cell cycle. Such proteins are ubiquitinated by ubiquitin ligases and then subsequently destroyed by the proteasome. The SCF (Skp1/Cullin/F-box) and the anaphase-promoting complex (APC) are two important ubiquitin ligases involved in cell cycle progression. While SCF is active throughout the cell cycle, APC gets activated during metaphase to anaphase transition. Cdc20 or Cdh1 binds to APC and...