How does E1 function in the ubiquitination process?
E1 functions by forming a thioester bond with ubiquitin, thereby activating it. The process involves two main steps:
ATP-dependent activation: E1 binds to ATP and ubiquitin, leading to the formation of an ubiquitin-adenylate intermediate. Thioester bond formation: The ubiquitin is transferred to a cysteine residue on E1, forming a high-energy thioester bond.
This activated ubiquitin is then transferred to an E2 enzyme, facilitating the ubiquitination of target proteins.
