Ubiquitin-conjugating enzyme
- Ubiquitin-conjugating enzyme
Ubiquitin-conjugating enzymes, also known as E2 enzymes and more rarely as "ubiquitin-carrier enzymes", perform the second step in the ubiquitination reaction that targets a protein for degradation via the proteasome.The ubiquitination process covalently attaches ubiquitin, a short protein of 76 amino acids, to a lysine residue on the target protein. Once a protein has been tagged with one ubiquitin molecule, additional rounds of ubiquitination form a polyubiquitin chain that is recognized by the proteasome's 19S regulatory particle, triggering the ATP-dependent unfolding of the target protein that allows passage into the proteasome's 20S core particle, where proteases degrade the target into short peptide fragments for recycling by the cell.
A ubiquitin-activating enzyme or E1 first activates the ubiquitin by covalently attaching the molecule to its active site cysteine residue. The activated ubiquitin is then transferred to an E2 cysteine. Once conjugated to ubiquitin, the E2 molecule binds one of several ubiquitin ligases or E3s via a structurally conserved binding region. The E3 molecule is responsible for binding the target protein substrate and transferring the ubiquitin from the E2 cysteine to a lysine residue on the target protein.[Nandi D, Tahiliani P, Kumar A, Chandu D. (2006). The ubiquitin-proteasome system. "J Biosci" Mar;31(1):137-55. PMID 16595883] ]A particular cell usually contains only a few types of E1 molecule, a greater diversity of E2s, and a very large variety of E3s. The E3 molecules responsible for substrate identification and binding are thus the mechanisms of substrate specificity in proteasomal degradation. Each type of E2 can associate with many E3s.[Risseeuw EP, Daskalchuk TE, Banks TW, Liu E, Cotelesage J, Hellmann H, Estelle M, Somers DE, Crosby WL. Protein interaction analysis of SCF ubiquitin E3 ligase subunits from Arabidopsis. "Plant J." 2003 Jun;34(6):753-67. PMID 12795696] ]ee also
* Ubiquitin-activating enzyme
* Ubiquitin-conjugating enzyme
* Ubiquitin ligase
References
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Ubiquitin-activating enzyme — Ubiquitin activating enzymes, also known as E1 enzymes, catalyze the first step in the ubiquitination reaction that targets a protein for degradation via the proteasome. The ubiquitination process covalently attaches ubiquitin, a short protein of … Wikipedia
Ubiquitin — is a highly conserved regulatory protein that is expressed in eukaryotes. Ubiquitination (or ubiquitylation) refers to the post translational modification of a protein by the covalent attachment (via an isopeptide bond) of one or more ubiquitin… … Wikipedia
Ubiquitin ligase — A ubiquitin ligase (also called an E3 ubiquitin ligase) is a protein that covalently attaches ubiquitin to a lysine on a target protein via an isopeptide bond. In general, the ubiquitin ligase is involved in polyubiquitination: A second ubiquitin … Wikipedia
Deubiquitinating enzyme — Deubiquitinating enzymes (DUBs) are a large group of proteases[1] (more than 60 known) that regulate ubiquitin dependent metabolic pathways by cleaving ubiquitin protein bonds. DUBs are also commonly referred to as deubiquitinating peptidases,… … Wikipedia
UBE2L3 — Ubiquitin conjugating enzyme E2L 3, also known as UBE2L3, is a human gene.cite web | title = Entrez Gene: UBE2L3 ubiquitin conjugating enzyme E2L 3| url = http://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene Cmd=ShowDetailView TermToSearch=7332|… … Wikipedia
UBE2I — Ubiquitin conjugating enzyme E2I (UBC9 homolog, yeast), also known as UBE2I, is a human gene. PBB Summary section title = summary text = The modification of proteins with ubiquitin is an important cellular mechanism for targeting abnormal or… … Wikipedia
UBE2D2 — Ubiquitin conjugating enzyme E2D 2 (UBC4/5 homolog, yeast), also known as UBE2D2, is a human gene.cite web | title = Entrez Gene: UBE2D2 ubiquitin conjugating enzyme E2D 2 (UBC4/5 homolog, yeast)| url = http://www.ncbi.nlm.nih.gov/sites/entrez?Db … Wikipedia
UBE2D1 — Ubiquitin conjugating enzyme E2D 1 (UBC4/5 homolog, yeast), also known as UBE2D1, is a human gene.cite web | title = Entrez Gene: UBE2D1 ubiquitin conjugating enzyme E2D 1 (UBC4/5 homolog, yeast)| url = http://www.ncbi.nlm.nih.gov/sites/entrez?Db … Wikipedia
UBE2V2 — Ubiquitin conjugating enzyme E2 variant 2, also known as UBE2V2, is a human gene.cite web | title = Entrez Gene: UBE2V2 ubiquitin conjugating enzyme E2 variant 2| url = http://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene Cmd=ShowDetailView… … Wikipedia
UBE2L6 — Ubiquitin conjugating enzyme E2L 6, also known as UBE2L6, is a human gene.cite web | title = Entrez Gene: UBE2L6 ubiquitin conjugating enzyme E2L 6| url = http://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene Cmd=ShowDetailView TermToSearch=9246|… … Wikipedia
