Ubiquitin-conjugating enzyme E2 (E2)

Ubiquitin-conjugating enzymes (E2s) play a central role in the process of ubiquitination, a type of post-translational modification where ubiquitin is transferred to a target protein. E2 enzymes interact with E1 (ubiquitin-activating enzymes) to receive ubiquitin and cooperate with E3 ligases, which determine substrate specificity, to catalyze the covalent attachment of ubiquitin to lysine residues of target proteins. This modification labels proteins for degradation by the proteasome, regulates protein localization, activity, and stability, and participates in key cellular processes including cell cycle regulation, DNA repair, and signal transduction. In humans, there are approximately 30 E2 enzymes, each capable of interacting with numerous E3 ligases, and each contributes to the diversity and specificity of protein ubiquitination. Aberrations in E2 enzyme activity are implicated in many diseases, including cancer and neurodegenerative disorders. Clarification: If the intent is to capture information about a specific E2 enzyme, such as UBE2I (also known as UBC9, associated with SUMOylation rather than ubiquitin conjugation), please specify; otherwise, the information above pertains to the general class of E2 ubiquitin-conjugating enzymes. Note: “Ubiquitin conjugating enzyme E2 I” is a nonstandard name: please cross-check for intended gene or protein designation or supply an accession number for accurate data mapping.

Other names

Ubiquitin-conjugating enzymeE2 enzymeUbiquitin-carrier enzymeUBE2I (if meant as the SUMO E2, UBC9)

Inhibition of E2 enzyme activity (blocks protein ubiquitination, stabilizes substrates); Disruption of E2–E3 interactions to alter ubiquitin transfer and substrate recognition.