VPS37 isoforms differentially modulate the ternary complex formation of ALIX, ALG-2, and ESCRT-I
Mayumi Okumura1, Angela M Katsuyama, Hideki Shibata
1Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University.
Bioscience, Biotechnology, and Biochemistry
|August 9, 2013
Summary
The endosomal sorting complex required for transport (ESCRT)-I complex interacts with ALG-2, a calcium-dependent adaptor protein. This interaction bridges ALIX and ESCRT-I, forming a crucial ternary complex for cellular functions.
Area of Science:
- Cell Biology
- Molecular Biology
- Protein Interactions
Background:
- The ESCRT system is vital for membrane trafficking, viral budding, and cell division.
- ESCRT-I, a core ESCRT complex, has four subunits, including four VPS37 isoforms.
- The role of ALG-2 as an adaptor protein in the ESCRT-I complex was previously unclear.
Purpose of the Study:
- To investigate the adaptor function of ALG-2 within the ESCRT-I complex.
- To determine how ALG-2 interacts with different VPS37 isoforms of ESCRT-I.
- To elucidate the mechanism by which ALG-2 bridges ALIX and ESCRT-I.
Main Methods:
- Far-Western blot analysis using a biotin-labeled ALG-2 probe.
- Pulldown assays with Strep-tagged ALG-2 and recombinant ESCRT-I complexes.
- In vitro binding assays using purified recombinant proteins.
Main Results:
- VPS37B and VPS37C isoforms of ESCRT-I showed stronger interaction with ALG-2 compared to TSG101.
- ALG-2 binds to ESCRT-I in a calcium-dependent manner.
- A ternary complex, ESCRT-I/ALIX/ALG-2, was formed, mediated by ALG-2.
Conclusions:
- ALG-2 acts as a calcium-dependent adaptor protein.
- ALG-2 bridges ALIX and ESCRT-I, facilitating the formation of a ternary complex.
- This interaction is significant for the functional role of the ESCRT system in cellular processes.
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