Tag: Ubiquitin-Proteasome system

K48‑linked ubiquitination is the principal degradation signal in eukaryotic cells, directing proteins to the 26S proteasome. Built by E1, E2 and E3 enzymes, K48‑linked chains regulate protein turnover, cell‑cycle progression and DNA‑damage responses, forming a central mechanism for maintaining proteostasis and preventing toxic protein accumulation.

The ubiquitin–proteasome system (UPS) regulates protein turnover and controls cell‑cycle progression, DNA repair, apoptosis and oncogenic signalling. In cancer, UPS components become dysregulated, leading to excessive degradation of tumour suppressors and stabilisation of oncogenic proteins. This imbalance drives tumour growth and makes UPS a powerful therapeutic target.

Protein degradation is a vital cellular process that removes damaged or unnecessary proteins to maintain homeostasis. This article explains the ubiquitin–proteasome system, autophagy, and their roles in cellular regulation and disease.

E3 ubiquitin ligases are key regulators of protein ubiquitination and cellular protein homeostasis. They provide substrate specificity within the ubiquitin system and regulate protein degradation, cell-cycle progression, DNA repair, immune signalling, apoptosis, and other essential cellular processes.