Mechanism for the selective conjugation of ubiquitin to phytochrome
The long term goal of this project is to understand at the molecular level how intracellular proteins are degraded. The purpose of this research is to characterize the form-dependent degradation of phytochrome as a model system for the study of selective protein breakdown. Phytochrome exists in two photo-interconveretible forms, a red-absorbing Pr form and a far-red absorbing Pfr form. Recent evidence indicates that selective breakdown of phytochrome in etiolated oat seedlings occurs by a ubiquitin-dependent proteolytic pathway. Ubiquitin is a 76 amino acid eukaryotic protein that is covalently ligated to proteins destined for catabolism and serves as recognition signal for proteases specific for ubiquitin-protein conjugates. In an attempt to understand why Pfr and not Pr is recognized by the ubiquitin pathway, we have characterized ubiquitin-phytochrome conjugates (Ub-P) with respect to their kinetics of accumulation, localization within the cell, and sites of ubiquitin attachment. We also examined Pfr degradation in etiolated seedlings from a variety of other plant species (corn, rye, pea and zucchini squash) for their ability to form Ub-P during Pfr degradation. 4 refs.
- Research Organization:
- Wisconsin Univ., Madison, WI (USA). Dept. of Horticulture
- Sponsoring Organization:
- DOE/ER
- DOE Contract Number:
- FG02-88ER13968
- OSTI ID:
- 6605340
- Report Number(s):
- DOE/ER/13968-T2; ON: DE90017561
- Country of Publication:
- United States
- Language:
- English
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Mechanism for the selective conjugation of ubiquitin to phytochrome