RING finger protein 4; E3 ubiquitin ligase RNF4; small nuclear ring finger protein; protein SNURF (RNF4, SNURF, RES4-26)
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Function
- E3 ubiquitin-protein ligase
- binds polysumoylated chains covalently attached to proteins & mediates Lys-6-, Lys-11-, Lys-48- & Lys-63-linked polyubiquitination of those substrates & their subsequent targeting to the proteasome for degradation
- regulates degradation of several proteins including PML & the transcriptional activator PEA3
- role in chromosome alignment & spindle assembly
- regulates the kinetochore CENPH-CENPI-CENPK complex by targeting polysumoylated CENPI to proteasomal degradation
- regulates cellular responses to hypoxia through degradation of EPAS1
- regulates cellular responses to heat shock through degradation of PARP1
- may also bind DNA/nucleosomes & have a more direct role in regulation of transcription, enhancing basal transcription & steroid receptor-mediated transcriptional activation
- protein modification; protein ubiquitination
- sumoylated; conjugated by one or two SUMO1 moieties
- autoubiquitinated (putative)
- homodimer (via RING-type Zn+2 finger domain)
- interacts with GSC2 (putative)
- interacts with AR/androgen receptor & TBP (putative)
- interacts with TCF20
- interacts with PATZ1
- interacts with TRPS1
- negatively regulates TRPS1 transcriptional repressor activity
- interacts with PML (SUMO1-dependent)
- interacts with PML (SUMO2-dependent)
- interacts with PARP1
Structure
- the RING-type Zn+2 finger domain is required for the ubiquitination of polysumoylated substrates (putative)
- contains 1 RING-type Zn+2 finger
Compartment
- cytoplasm, nucleus, nucleoplasm, PML body
Expression
- widely expressed at low levels in many tissues
- highly expressed in testis