Ubiquitin-conjugating enzymes, also known as E2 enzymes, play a crucial role in the process of protein degradation and regulation within cells. They facilitate the transfer of a small protein called ubiquitin to target proteins, marking them for degradation by the proteasome or altering their function. This process is essential for maintaining cellular homeostasis and regulating various biological processes. These enzymes work in conjunction with ubiquitin-activating enzymes (E1) and ubiquitin ligases (E3) to ensure that proteins are tagged appropriately. The activity of E2 enzymes is vital for cellular responses to stress, cell cycle regulation, and the removal of damaged proteins, highlighting their importance in overall cellular health.