ubiquitin

(noun)

A small regulatory protein sequence that directs proteins to specific compartments within the cell. Specifically, a ubiquitin tag directs the protein to a proteasome, which destroys and recycles the components.

Related Terms

Examples of ubiquitin in the following topics:

  • Two-Hybrid Analysis

    • The split-ubiquitin system provides a method for overcoming this limitation.
    • In the split-ubiquitin system, two integral membrane proteins to be studied are fused to two different ubiquitin moieties: a C-terminal ubiquitin moiety ("Cub", residues 35–76) and an N-terminal ubiquitin moiety ("Nub", residues 1–34).
    • In addition to being fused to an integral membrane protein, the Cub moiety is also fused to a transcription factor (TF) that can be cleaved off by ubiquitin specific proteases.
    • Upon bait–prey interaction, Nub and Cub-moieties assemble, reconstituting the split-ubiquitin.
    • The reconstituted split-ubiquitin molecule is recognized by ubiquitin specific proteases, which cleave off the reporter protein, allowing it to induce the transcription of reporter genes.

  • Proteolytic Degradation

    • This ubiquitin sequence is a modification to proteins that are targeted for degradation.
    • The recognition of this ubiquitin signal by the proteasome results in degradation of the protein into its amino acids, which are then recycled and reused for the synthesis of new proteins.
    • The protein is tagged with several ubiquitin signals that target the proteasome.

  • Proteomics

    • Not only does the translation from mRNA cause differences, but many proteins are also subjected to a wide variety of chemical modifications after translation which are critical to the protein's function such as phosphorylation, ubiquitination, methylation, acetylation, glycosylation, oxidation, and nitrosylation.