E3 Ubiquitin Ligase is an essential enzyme in the process of protein degradation within cells. It plays a critical role in the ubiquitin-proteasome pathway, where it facilitates the attachment of ubiquitin molecules to target proteins. This tagging process signals that the protein should be marked for degradation, helping to regulate various cellular functions and maintain protein homeostasis. The E3 ligase is known for its specificity, as it can recognize and bind to particular substrates, ensuring that only certain proteins are tagged for destruction. This selectivity is crucial for processes such as cell cycle regulation, DNA repair, and responses to stress, making E3 ligases vital for overall cellular health and function.