ubiquitin activating enzyme activity

Definition

Target type: molecularfunction

Catalysis of the reaction: E1 + ubiquitin + ATP--> E1-ubiquitin + AMP + PPi, where the E1-ubiquitin linkage is a thioester bond between the C-terminal glycine of Ub and a sulfhydryl side group of an E1 cysteine residue. This is the first step in a cascade of reactions in which ubiquitin is ultimately added to a protein substrate. [GOC:BioGRID, Wikipedia:Ubiquitin-activating_enzyme]

Ubiquitin activating enzyme activity (E1) is the first step in the ubiquitination pathway, a critical cellular process that tags proteins for various cellular fates. It involves the ATP-dependent activation of ubiquitin, a small protein that acts as a molecular tag. The E1 enzyme first binds to ubiquitin and utilizes ATP to form a high-energy thioester bond between its active site cysteine residue and the carboxyl terminus of ubiquitin. This activated ubiquitin molecule is then transferred to a ubiquitin conjugating enzyme (E2) through another thioester bond. This process of ubiquitin activation is essential for subsequent steps in the ubiquitination cascade, including the conjugation of ubiquitin to target proteins by E2 and E3 enzymes. The E1 enzyme plays a crucial role in regulating protein turnover, signal transduction, DNA repair, and immune responses. Mutations in E1 enzymes can lead to various diseases, including cancer and neurodegenerative disorders.'
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Proteins (5)

Compounds (7)