COP1: Proteins and Enzymes

COP1 is an E3 ubiquitin-protein ligase that mediates ubiquitination and subsequent proteasomal degradation of target proteins. It is directly involved in p53 ubiquitination and degradation, thereby abolishing p53-dependent transcription and apoptosis. It ubiquitinates p53 independently of MDM2 or RCHY1. It probably mediates E3 ubiquitin ligase activity by functioning as the essential RING domain subunit of larger E3 complexes. In contrast, it does not constitute the catalytic RING subunit in the DCX DET1-COP1 complex that negatively regulates JUN, where the ubiquitin ligase activity is mediated by RBX1.