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The HECT family has a HECT domain in which a conserved Cys residue forms a thioester bond with the ubiquitin carried by E2, and E2 first transfers ubiquitin to E3, which is then presented to the substrate by E3.
Ubiquitinated enzyme
Ubiquitin-activating enzyme E1 Ubiquitin-binding enzyme E2 Ubiquitin ligase E3
The ubiquitin ligase E3 is divided into the HECT family and the RING-finger family:
4. The ubiquitinated protein is recognized and bound by a specific proteasome, and finally the protein is decomposed into short peptides or amino acids under the catalysis of proteases.
2. E1 delivers the activated ubiquitin to the ubiquitin-binding enzyme E2 through a lactide process.
3. Ubiquitin ligase E3 binds E2 ubiquitin to the target protein and releases E2 to form a specific ubiquitinated protein.
Protein ubiquitination
Ubiquitination
Ubiquitination refers to the process by which ubiquitin (a class of low molecular weight proteins) molecules classify proteins in cells under a series of special enzymes, select target protein molecules, and specifically modify target proteins.
E3 of the RING-finger family contains a similar E2 binding domain, which acts as a bridge to transfer activated ubiquitin from E2 directly to the target protein, which itself does not interact with ubiquitin.
Ubiquitination plays an important role in the localization, metabolism, function, regulation and degradation of proteins. At the same time, it is also involved in the regulation of cell cycle, proliferation, apoptosis, differentiation, metastasis, gene expression, transcriptional regulation, signal transmission, damage repair, inflammatory immunity and almost all life activities.
Biblioteka Baidu
How is the protein ubiquitinated?
1. Activation of ubiquitin: The carboxyl group at the ubiquitin glycine end is linked to the thiol group of the ubiquitin-activating enzyme E1. This step requires ATP as an energy to finally form a thioester bond between ubiquitin and the ubiquitin-activating enzyme E1.
