J Korean Cancer Assoc.  2000 Apr;32(2):417-421.

Proteolytic Regulation of Retinoblastoma Family Protein p107 by Ubiquitin - proteasome Pathway

• Jang JS
• Park BK
• Hwang SG

Abstract

PURPOSE: Proteolysis is an important way to regulate cell cycle regulatory proteins. Ubiquitin- proteasome pathway regards as highly selective proteolytic machinary mostly in physiological state. We investigated the role of ubiquitin-proteasome pathway in p107 protein degradation.
MATERIALS AND METHODS
p107 protein level was determined by western blot analysis in Ewings sarcoma cell line incubated with HMG-CoA inhibitor lovastatin. Recovery of p107 protein was determined with inhibitors of proteasome, serine protease or caspase. Ubiquitination of p107 protein was assessed by ubiquitin western analysis.
RESULTS
pl07 protein level was decreased with lovastin and its proteolytic effect was counteracted with proteasome inhibitors. Ubiquitin western analysis showed p107 protein fragments were tagged with ubiquitin and it was more evident with specific proteasome inhibitor lactacystin.
CONCLUSION
Lovastatin drives p107 protein to be degraded. In a certain circumstance proteolysis of p107 protein was executed by ubiquitin-proteasome pathway.

Keyword

p107 protein; Proteolysis; Ubiquitin-proteasome pathway

MeSH Terms

Blotting, Western
Cell Cycle Proteins
Cell Line
Humans
Lovastatin
Proteasome Endopeptidase Complex*
Proteasome Inhibitors
Proteolysis
Retinoblastoma*
Sarcoma, Ewing
Serine Proteases
Ubiquitin*
Ubiquitination
Cell Cycle Proteins
Lovastatin
Proteasome Endopeptidase Complex
Proteasome Inhibitors
Serine Proteases
Ubiquitin