| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
|
|
|
|||||||
|
|||||||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Articles in PresS, published online ahead of print December 4, 2001
Am J Physiol Endocrinol Metab, 10.1152/ajpendo.00511.2001
Submitted on November 12, 2001
Accepted on November 29, 2001
1 Medicine, Polypeptide Laboratory, McGill University, Montreal, Quebec, Canada
* To whom correspondence should be addressed. E-mail: simon.wing{at}mcgill.ca.
The activity of the ubiquitin-dependent proteolytic system in differentiated tissues under basal conditions remains poorly explored. We measured rates of ubiquitination in rat tissue extracts. Accumulation of ubiquitinated proteins increased in the presence of ubiquitin aldehyde, indicating that deubiquitinating enzymes can regulate ubiquitination. Rates of ubiquitination varied four fold, the highest rate in the testis. We tested whether ubiquitin activating enzyme (E1) or ubiquitin conjugating enzymes (E2s) could be limiting for conjugation. Immunodepletion of UBC2 or UBC4 lowered rates of conjugation similarly. Supplementation of extracts with excess UBC2 or UBC4, but not E1, stimulated conjugation. However, UBC2 stimulated rates of ubiquitination still differed amongst tissues indicating that tissue differences in E3s or substrate availability may also be rate controlling. UBC2 and UBC4 stimulated conjugation half-maximally at concentrations of 10-50 nM and 28-44 nM respectively. Endogenous tissue levels of UBC2, but not UBC4 appeared saturating for conjugation suggesting that in vivo modulation of UBC4 levels can likely control ubiquitin conjugation. Thus, the pool of ubiquitin conjugates and therefore the rate of degradation of proteins by this system may be controlled by E2s, E3s, and isopeptidases. The regulation of the ubiquitin pathway appears complex, but precise.
This article has been cited by other articles:
|
|
 |
|
  E. Vazeille, A. Codran, A. Claustre, J. Averous, A. Listrat, D. Bechet, D. Taillandier, D. Dardevet, D. Attaix, and L. Combaret The ubiquitin-proteasome and the mitochondria-associated apoptotic pathways are sequentially downregulated during recovery after immobilization-induced muscle atrophy Am J Physiol Endocrinol Metab, November 1, 2008; 295(5): E1181 - E1190. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 X. Yu, S. Hong, and E. M. Faustman Cadmium-induced Activation of Stress Signaling Pathways, Disruption of Ubiquitin-dependent Protein Degradation and Apoptosis in Primary Rat Sertoli Cell-Gonocyte Cocultures Toxicol. Sci., August 1, 2008; 104(2): 385 - 396. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Luo, M. Koh, J. Feng, Q. Wu, and P. Melamed Cross Talk in Hormonally Regulated Gene Transcription through Induction of Estrogen Receptor Ubiquitylation Mol. Cell. Biol., August 15, 2005; 25(16): 7386 - 7398. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. Kwon, K. Mochida, Y.-L. Wang, S. Sekiguchi, T. Sankai, S. Aoki, A. Ogura, Y. Yoshikawa, and K. Wada Ubiquitin C-Terminal Hydrolase L-1 Is Essential for the Early Apoptotic Wave of Germinal Cells and for Sperm Quality Control During Spermatogenesis Biol Reprod, July 1, 2005; 73(1): 29 - 35. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 X. Huang, H. Wang, M. Xu, L. Lu, Z. Xu, J. Li, Z. Zhou, and J. Sha Expression of a Novel RAD23B mRNA Splice Variant in the Human Testis J Androl, May 1, 2004; 25(3): 363 - 368. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
O. A. J. Adegoke, N. Bedard, H. P. Roest, and S. S. Wing Ubiquitin-conjugating enzyme E214k/HR6B is dispensable for increased protein catabolism in muscle of fasted mice Am J Physiol Endocrinol Metab, September 1, 2002; 283(3): E482 - E489. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
| Visit Other APS Journals Online |
