E2 (ubiquitin-conjugating enzyme)

E2, or ubiquitin-conjugating enzyme, is a protein that plays a key role in the process of tagging other proteins for destruction or regulation in the cell. It works by transferring a small protein called ubiquitin to specific target proteins, marking them for degradation or altering their activity. E2 acts as a mediator between the initial tagging enzyme (E1) and the final attachment enzyme (E3), ensuring that proteins are properly marked for cellular processes such as protein turnover, signal regulation, and DNA repair. This system maintains cellular health by controlling protein levels and activities.