UBQ

Ubiquitin homologues
UBQ
SMART accession number:SM00213
Description: Ubiquitin-mediated proteolysis is involved in the regulated turnover of proteins required for controlling cell cycle progression
Interpro abstract (IPR000626):

Ubiquitin is a globular protein, the last four C-terminal residues (Leu-Arg-Gly-Gly) extending from the compact structure to form a 'tail', important for its function. The latter is mediated by the covalent conjugation of ubiquitin to target proteins, by an isopeptide linkage between the C-terminal glycine and the epsilon amino group of lysine residues in the target proteins.

Ubiquitin is a protein of 76 amino acid residues, found in all eukaryotic cells and whose sequence is extremely well conserved from protozoan to vertebrates. Ubiquitin acts through its post-translational attachment (ubiquitinylation) to other proteins, where these modifications alter the function, location or trafficking of the protein, or targets it for destruction by the 26S proteasome [ (PUBMED:15454246) ].

Ubiquitin is expressed as three different precursors: a polymeric head-to-tail concatemer of identical units (polyubiquitin), and two N-terminal ubiquitin moieties, UbL40 and UbS27, that are fused to the ribosomal polypeptides L40 and S27, respectively. Specific endopeptidases cleave these precursor molecules [ (PUBMED:15571815) ] to release ubiquitin moieties that are identical in sequence and contribute to the ubiquitin pool [ (PUBMED:16185873) ]. Some organisms express additional ubiquitin fusion proteins [ (PUBMED:12729753) ]. Furthermore, there are several ubiquitin-like proteins derived from ubiquitin [ (PUBMED:12826404) ].

This entry represents a domain characteristic of ubiquitin (Ub) and ubiquitin-like (Ubl) proteins such as SUMO [ (PUBMED:17491593) (PUBMED:15479240) ] and Nedd8 [ (PUBMED:9857030) ].

GO function:protein binding (GO:0005515)
Family alignment:
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There are 49174 UBQ domains in 38515 proteins in SMART's nrdb database.

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