E3 Enzymes are a type of enzyme that play a crucial role in the process of protein ubiquitination. They are responsible for transferring ubiquitin molecules to target proteins, marking them for degradation or altering their function. This process is essential for maintaining cellular homeostasis and regulating various biological functions. These enzymes are part of a larger family of enzymes, including E1 (ubiquitin-activating enzymes) and E2 (ubiquitin-conjugating enzymes). Together, they form a complex system that controls protein turnover and signaling pathways within cells. Dysregulation of E3 Enzymes can lead to various diseases, including cancer and neurodegenerative disorders.