constitutive photomorphogenic protein 1 (E3 ubiquitin-protein ligase RFWD2, RING finger & WD repeat domain protein 2, RFWD2)

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Function

E3 ubiquitin-protein ligase
mediates ubiquitination & subsequent proteasomal degradation of target proteins
role in JUN ubiquitination & degradation
role in p53 (TP53) ubiquitination & degradation, thereby abolishing p53-dependent transcription & apoptosis
ubiquitinates p53 independently of MDM2 or RCHY1
probably mediates E3 ubiquitin ligase activity by functioning as the essential RING domain subunit of larger E3 complexes
in contrast, it does not constitute the catalytic RING subunit in the DCX DET1-COP1 complex that negatively regulates JUN, the ubiquitin ligase activity being mediated by RBX1
protein degradation; protein ubiquitinylation
component of the DCX DET1-COP1 ubiquitin ligase complex
isoform 2 does not interact with CUL4A but still binds to RBX1, suggesting that the interaction may be mediated by another cullin protein
isoform 1 & isoform 2 interact with CUL5 but not with CUL1, CUL2, CUL3
interacts with bZIP transcription factors JUN, JUNB & JUND but not with FOS, ATF2 nor XBP1
interacts with p53 (TP53)

homodimer
homodimerization is mediated by the coiled coil domain
RING finger domain, in addition to its role in ubiquitination, functions as a structural scaffold to bring two clusters of positive-charged residues within spatial proximity to mimic a bipartite nuclear localization signal (NLS)
belongs to the COP1 family
contains 1 RING-type Zn+2 finger
contains 7 WD repeats