Ubiquitination involves the sequential action of three enzymes: E1 ubiquitin-activating enzyme, E2 ubiquitin-conjugating enzyme, and E3 ubiquitin ligase. The process begins with the E1 enzyme activating ubiquitin and transferring it to the E2 enzyme, followed by the E3 enzyme mediating the transfer of ubiquitin from the E2 enzyme to the target protein. Through the regulation of the ubiquitin-proteasome system (UPS), cells can promptly clear damaged or obsolete proteins, preventing their accumulation and the formation of toxic aggregates. Additionally, ubiquitination participates in regulating key nodes within cell signaling pathways, such as the NF-κB signaling pathway and the PI3K/Akt pathway. In this way, ubiquitination events impact various cellular functions, including growth, differentiation, and response to environmental stress.