Related Experiment Videos
NF-kappa B p105 processing via the ubiquitin-proteasome pathway
1Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
The Journal of Biological Chemistry
|January 27, 1998
Summary
The ubiquitin-proteasome pathway is crucial for processing the p105 precursor into the p50 subunit of NF-kappa B in yeast. Yeast mutants affecting proteasome function, but not specific ubiquitin conjugating enzymes, inhibit this essential protein processing.
Area of Science:
- Molecular Biology
- Cell Biology
- Biochemistry
Background:
- The p50 subunit of NF-kappa B is derived from a 105-kDa precursor (p105) through proteolytic processing.
- This processing occurs in both yeast and mammalian cells, but the precise mechanisms are not fully understood.
Purpose of the Study:
- To investigate the role of the ubiquitin-proteasome pathway in the processing of p105 in yeast.
- To identify specific components of the ubiquitin-proteasome system involved in p105 processing.
Main Methods:
- Utilized yeast mutants defective in various aspects of the ubiquitin-proteasome pathway, including proteasome subunits, regulatory ATPases, and associated enzymes.
- Analyzed the accumulation of ubiquitinated intermediates and assessed the impact of mutations on p105 processing.
Main Results:
- Yeast mutants affecting the 20S proteasome, 19S regulatory complex ATPases, and proteasome-associated isopeptidase (Doa4) significantly inhibited p105 processing.
- Accumulation of ubiquitinated p105 intermediates in certain mutants indicated ubiquitination is necessary for processing.
- Mutations in ubiquitin conjugating enzymes or the N-end rule pathway did not affect p105 processing.
- A region of p105 crucial for processing in mammalian cells was found to be dispensable in yeast.
Conclusions:
- The ubiquitin-proteasome pathway is essential for p105 processing in yeast, similar to mammalian cells.
- While the overall requirement for the ubiquitin-proteasome system is conserved, specific molecular mechanisms for p105 processing differ between yeast and mammalian systems.