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RING fingers mediate ubiquitin-conjugating enzyme (E2)-dependent ubiquitination
K L Lorick1, J P Jensen, S Fang
1Laboratory of Immune Cell Biology, Division of Basic Sciences, National Cancer Institute, Building 10, Room 1B34, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892-1152, USA.
Summary
Researchers identified a RING finger protein (AO7) involved in ubiquitination. This process, crucial for protein regulation, was confirmed for multiple RING finger proteins, suggesting a broad role for these domains in controlling protein levels.
Area of Science:
- Biochemistry
- Molecular Biology
- Cellular Biology
Background:
- Ubiquitination is a key post-translational modification regulating protein stability and function.
- RING finger domains are found in various proteins, but their direct role in ubiquitination is not fully understood.
Purpose of the Study:
- To identify and characterize RING finger proteins involved in E2-dependent ubiquitination.
- To investigate the role of the RING finger domain in mediating ubiquitination.
Main Methods:
- Identification of AO7, a RING finger protein that binds ubiquitin-conjugating enzymes (E2s).
- Site-directed mutagenesis of cation-coordinating residues within the RING finger of AO7.
- Zinc chelation assays.
- Assessment of ubiquitination activity for multiple RING finger proteins (BRCA1, Siah-1, TRC8, NF-X1, kf-1, Praja1).
Main Results:
- AO7 was identified as a substrate for E2-dependent ubiquitination.
- Mutations in AO7's RING finger or zinc chelation abolished ubiquitination.
- All tested RING finger proteins, including BRCA1 and Siah-1, facilitated E2-dependent ubiquitination.
- The RING finger domain was directly implicated in this ubiquitination activity.
Conclusions:
- The RING finger domain is a critical functional unit for mediating E2-dependent ubiquitination.
- A diverse range of RING finger proteins may play significant roles in protein level regulation through ubiquitination.
- These findings reveal a previously unappreciated function for many RING finger proteins in cellular processes.