Hect E3 ubiquitin ligases are a type of enzyme that play a crucial role in the process of ubiquitination, which tags proteins for degradation or alters their function. They transfer ubiquitin, a small protein, to target proteins, marking them for destruction by the proteasome or influencing their activity and location within the cell. These ligases are characterized by their HECT (Homologous to the E6-AP Carboxyl Terminus) domain, which is essential for their function. Hect E3 ligases are involved in various cellular processes, including cell cycle regulation, DNA repair, and responses to stress, making them important for maintaining cellular health.