The Ubiquitin Activating Enzyme (E1) is a crucial component in the ubiquitin-proteasome pathway, which is essential for protein degradation. E1 catalyzes the first step in the ubiquitination process by activating ubiquitin in an ATP-dependent manner. This activation is a prerequisite for the subsequent steps involving E2 (ubiquitin-conjugating enzyme) and E3 (ubiquitin ligase).
