Ubiquitination is a critical post-translational modification in eukaryotic cells, mediated by a sequential enzymatic cascade involving E1 (activating), E2 (conjugating), and E3 (ligase) enzymes that catalyze the covalent conjugation of ubiquitin to substrate proteins. This modification precisely controls substrate stability, localization, and function, thereby governing fundamental cellular processes such as the cell cycle, DNA repair, and apoptosis. Deubiquitinating enzymes (DUBs) counteract ub