TOPORS
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.
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.
None
The disease is caused by variants affecting the gene represented in this entry.
Post-translational modifications
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.
Tissue Specificity
Expressed at highest levels in testis and at lower levels in adrenal gland, bone marrow, brain, colon, heart, kidney, liver, muscle, ovary, pancreas, placenta, prostate, skeletal muscle, skin, small intestine, spleen, stomach, testis, thymus, thyroid and uterus. Expressed in the alveolar epithelium of the lung. Expression is commonly decreased in colon adenocarcinomas and lung cancers.
Cellular localization
- Nucleus
- Nucleus
- PML body
- Localizes to discrete nuclear foci which partly overlap with PML nuclear bodies. Targeted to PML nuclear bodies upon DNA damage.
Alternative names
LUN, TP53BPL, TOPORS, E3 ubiquitin-protein ligase Topors, RING-type E3 ubiquitin transferase Topors, SUMO1-protein E3 ligase Topors, Topoisomerase I-binding RING finger protein, Topoisomerase I-binding arginine/serine-rich protein, Tumor suppressor p53-binding protein 3, p53-binding protein 3, p53BP3