RNF4 Protein, Human (Active, 71a.a)

RNF4 Protein operates as an E3 ubiquitin-protein ligase with a distinctive ability to bind polysumoylated chains covalently attached to proteins, facilitating the 'Lys-6', 'Lys-11', 'Lys-48', and 'Lys-63'-linked polyubiquitination of its substrates. These substrates are subsequently targeted for proteasomal degradation, contributing to the regulation of various cellular processes. RNF4 plays a role in the degradation of proteins such as PML and the transcriptional activator PEA3. In the context of chromosome dynamics, it influences kinetochore assembly, specifically targeting polysumoylated CENPI for proteasomal degradation and thereby impacting chromosome alignment and spindle assembly. Furthermore, RNF4 is implicated in cellular responses to hypoxia and heat shock, facilitating the degradation of EPAS1 and PARP1, respectively. Additionally, RNF4 may interact with DNA/nucleosomes, suggesting a potential direct involvement in transcriptional regulation, including the enhancement of basal transcription and steroid receptor-mediated transcriptional activation. Notably, it catalyzes the ubiquitination of sumoylated PARP1 in response to PARP1 trapping to chromatin, leading to the removal of PARP1 from chromatin facilitated by VCP/p97.