Description
Ubiquitin-activating enzyme 1 (UBA1) catalyzes the first step in ubiquitin conjugation to mark cellular proteins for degradation through the ubiquitin-proteasome system. UBA1 activates ubiquitin by first adenylating its C-terminal glycine residue with ATP, and thereafter linking this residue to the side chain of a cysteine residue in E1, yielding a ubiquitin-E1 thioester and free AMP. Posttranslational modification by ubiquitin or ubiquitin-like proteins regulates numerous processes, including cell division, immune responses and embryonic development