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 ubiquitin conjugating enzymes is vital for processes such as cell cycle regulation, DNA repair, and responses to stress, highlighting their importance in cellular function and health.