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Updated: Jul 16, 2026

Immunofluorescence Analysis of Endogenous and Exogenous Centromere-kinetochore Proteins
Published on: March 3, 2016
PARC and CUL7 form atypical cullin RING ligase complexes.
Jeffrey R Skaar1, Laurence Florens, Takeya Tsutsumi
1Department of Medical Oncology, Dana-Farber Cancer Institute, 44 Binney Street, Boston, MA 02115, USA.
The study reveals that PARC, a protein related to PARKin, forms distinct complexes with CUL7, influencing ubiquitin ligase activity. These PARC- and CUL7-containing complexes are regulated, with multiple subcomplexes showing E3 ubiquitin ligase activity.
Area of Science:
- Molecular Biology
- Protein Biochemistry
- Genetics
Background:
- CUL7 and PARC (p53-associated, PARKin-like cytoplasmic protein) form dimers, but PARC's role in SCF-like complexes is unclear.
- CUL7-based SCF-like complexes exist, but PARC's interaction with these and its own complex formation require further investigation.
Purpose of the Study:
- To characterize PARC-containing complexes and their assembly with CUL7.
- To determine if PARC can form an SCF-like complex and how it interacts with CUL7-based complexes.
Main Methods:
- Tandem affinity purification (TAP)
- Multidimensional protein identification technology (MudPIT)
- In vitro E3 ubiquitin ligase activity assays
- Analysis of Parc-/-, Fbxw8-/- mice
Main Results:
- PARC binds RBX1 and is modified by NEDD8, confirming it as a cullin, but does not bind SKP1 or F-box proteins.
- CUL7 interaction with FBXW8 is mutually exclusive with CUL7 binding to PARC or p53.
- CUL7-PARC heterodimers bind p53, but p53 is not essential for CUL7-PARC dimerization.
- Parc-/-, Fbxw8-/- mice showed no phenotype exacerbation, suggesting functional separation.
- All examined PARC and CUL7 subcomplexes demonstrated E3 ubiquitin ligase activity in vitro.
Conclusions:
- PARC is a true cullin that forms distinct complexes with CUL7, separate from FBXW8.
- The assembly of PARC- and CUL7-containing complexes is tightly regulated.
- Multiple PARC- and CUL7-containing subcomplexes possess E3 ubiquitin ligase activity.
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