Noun
English Wikipedia has an article on:ubiquitinWikipedia
ubiquitin (plural ubiquitins)
(biochemistry) Any of a class of small protein, or polypeptide, present in the cells of all eukaryotes, that play a part in modifying and degrading proteins.
Altering the chain conformations exposes and conceals different parts of the ubiquitin protein, and the different linkages are recognized by proteins that are specific for the unique topologies that are intrinsic to the linkage. Source: Internet
Each end of the core particle associates with a 19S regulatory subunit that contains multiple ATPase active sites and ubiquitin binding sites; it is this structure that recognizes polyubiquitinated proteins and transfers them to the catalytic core. Source: Internet
DUBs cleave these proteins to produce active ubiquitin. Source: Internet
First, a ubiquitin molecule is bonded by its C-terminus to a specific lysine residue on the target protein. Source: Internet
Following addition of a single ubiquitin moiety to a protein substrate, further ubiquitin molecules can be added to the first, yielding a polyubiquitin chain. Source: Internet
HIF is synthesized consititutively, and hydroxylation of at least one of two critical proline residues mediates their interaction with the von Hippel Lindau E3 ubiquitin ligase complex, which targets them for rapid degradation. Source: Internet