Intracellular foreign or aberrant host proteins are cleaved into peptide fragments of a precise size, such that they can be loaded on to class I MHC molecules and presented externally to cytotoxic T cells. The ubiquitin-26S proteasome system plays a central role in the generation of these class I MHC antigens. <br>Ubiquitination is the mechanism of adding ubiquitin to lysine residues on substrate protein leading to the formation of a polyubiquitinated substrate. This process involves three classes of enzyme, an E1 ubiquitin-activating enzyme, an E2 ubiquitin-conjugating enzyme, and an E3 ubiquitin ligase. Polyubiquitination through lysine-48 (K48) generally targets the substrate protein for proteasomal destruction. The protease responsible for the degradation of K48-polyubiquitinated proteins is the 26S proteasome. This proteasome is a two subunit protein complex composed of the 20S (catalytic core) and 19S (regulatory) proteasome complexes. The proteasome eliminates most of the foreign and non-functional proteins from the cell by degrading them into short peptides; only a small fraction of the peptides generated are of the correct length to be presented by the MHC class I system. It has been calculated that between 994 and 3122 protein molecules have to be degraded for the formation of a single, stable MHC class I complex at the cell surface, with an average effciency of 1 in 2000 (Kloetzel et al. 2004, Princiotta et al. 2003). Reviewed: Elliott, T, 2011-02-10 Authored: Garapati, P V, 2010-10-29 Edited: Garapati, P V, 2010-10-29

http://purl.obolibrary.org/obo/HINO_0022372

Intracellular foreign or aberrant host proteins are cleaved into peptide fragments of a precise size, such that they can be loaded on to class I MHC molecules and presented externally to cytotoxic T cells. The ubiquitin-26S proteasome system plays a central role in the generation of these class I MHC antigens.
Ubiquitination is the mechanism of adding ubiquitin to lysine residues on substrate protein leading to the formation of a polyubiquitinated substrate. This process involves three classes of enzyme, an E1 ubiquitin-activating enzyme, an E2 ubiquitin-conjugating enzyme, and an E3 ubiquitin ligase. Polyubiquitination through lysine-48 (K48) generally targets the substrate protein for proteasomal destruction. The protease responsible for the degradation of K48-polyubiquitinated proteins is the 26S proteasome. This proteasome is a two subunit protein complex composed of the 20S (catalytic core) and 19S (regulatory) proteasome complexes. The proteasome eliminates most of the foreign and non-functional proteins from the cell by degrading them into short peptides; only a small fraction of the peptides generated are of the correct length to be presented by the MHC class I system. It has been calculated that between 994 and 3122 protein molecules have to be degraded for the formation of a single, stable MHC class I complex at the cell surface, with an average effciency of 1 in 2000 (Kloetzel et al. 2004, Princiotta et al. 2003).

Reviewed: Elliott, T, 2011-02-10

Authored: Garapati, P V, 2010-10-29

Edited: Garapati, P V, 2010-10-29

Pubmed20351195

Reactome, http://www.reactome.org

Pubmed19489725

Pubmed17145306

Pubmed12648452

Pubmed11917093

Pubmed14734113

Antigen processing: Ubiquitination & Proteasome degradation

http://purl.obolibrary.org/obo/NCBITaxon_9606

HINO:0022372

Antigen processing: Ubiquitination & Proteasome degradation

Reactome Database ID Release 43983168

GENE ONTOLOGYGO:0000209

ReactomeREACT_75842

http://purl.obolibrary.org/obo/INO_0000021

http://purl.obolibrary.org/obo/HINO_0018265

http://purl.obolibrary.org/obo/HINO_0018267

http://purl.obolibrary.org/obo/HINO_0018268

http://purl.obolibrary.org/obo/HINO_0018269

http://purl.obolibrary.org/obo/HINO_0018263

http://purl.obolibrary.org/obo/HINO_0017772

http://purl.obolibrary.org/obo/HINO_0017770

http://purl.obolibrary.org/obo/HINO_0018270