TOPORS

TOPORS is a nuclear protein which is serine and arginine rich, and contains a RING-type zinc finger domain. TOPORS is highly expressed in the testis, and plays a role as an ubiquitin-protein E3 ligase. Mutations in TOPORS are associated with retinitis pigmentosa type 31.

Full Name

topoisomerase I binding, arginine/serine-rich

Function

Functions as an E3 ubiquitin-protein ligase and as an E3 SUMO1-protein ligase. Probable tumor suppressor involved in cell growth, cell proliferation and apoptosis that regulates p53/TP53 stability through ubiquitin-dependent degradation. May regulate chromatin modification through sumoylation of several chromatin modification-associated proteins. May be involved in DNA damage-induced cell death through IKBKE sumoylation.

Biological Process

Biological Process cellular response to DNA damage stimulus Source:UniProtKB1 Publication
Biological Process DNA-templated transcription Source:UniProtKB1 Publication
Biological Process intrinsic apoptotic signaling pathway in response to DNA damage Source:UniProtKB1 Publication
Biological Process intrinsic apoptotic signaling pathway in response to DNA damage by p53 class mediator Source:Ensembl
Biological Process maintenance of protein location in nucleus Source:UniProtKB1 Publication
Biological Process negative regulation of apoptotic process Source:BHF-UCLBy Similarity
Biological Process photoreceptor cell outer segment organization Source:BHF-UCLBy Similarity
Biological Process positive regulation of DNA-templated transcription Source:Ensembl
Biological Process positive regulation of ubiquitin-protein transferase activity Source:BHF-UCL1 Publication
Biological Process proteasome-mediated ubiquitin-dependent protein catabolic process Source:UniProtKB1 Publication
Biological Process protein K48-linked ubiquitination Source:BHF-UCL1 Publication
Biological Process protein localization to nucleus Source:UniProtKB1 Publication
Biological Process protein monoubiquitination Source:BHF-UCL1 Publication
Biological Process protein polyubiquitination Source:BHF-UCL1 Publication
Biological Process protein sumoylation Source:UniProtKB1 Publication
Biological Process regulation of cell population proliferation Source:Ensembl
Biological Process retina layer formation Source:BHF-UCLBy Similarity
Biological Process retinal cone cell development Source:BHF-UCLBy Similarity
Biological Process retinal rod cell development Source:BHF-UCLBy Similarity
Biological Process ubiquitin-dependent protein catabolic process Source:UniProtKB1 Publication

Cellular Location

Nucleus
Nucleus, PML body
Localizes to discrete nuclear foci which partly overlap with PML nuclear bodies. Targeted to PML nuclear bodies upon DNA damage.

Involvement in disease

Retinitis pigmentosa 31 (RP31):
A retinal dystrophy belonging to the group of pigmentary retinopathies. Retinitis pigmentosa is characterized by retinal pigment deposits visible on fundus examination and primary loss of rod photoreceptor cells followed by secondary loss of cone photoreceptors. Patients typically have night vision blindness and loss of midperipheral visual field. As their condition progresses, they lose their far peripheral visual field and eventually central vision as well.

PTM

Phosphorylation at Ser-98 regulates the E3 ubiquitin-protein ligase activity but not the SUMO1-protein ligase activity. Phosphorylation at Ser-718 increases the E3 ubiquitin-protein ligase activity versus the SUMO1-protein ligase activity resulting in increased p53/TP53 ubiquitination and degradation.
Sumoylated.