Ubiquitin--more than just a signal for protein degradation.
D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D017360:Arabidopsis; D002352:Carrier Proteins; D004330:Drosophila; D004705:Endocytosis; D004721:Endoplasmic Reticulum / Q000378:metabolism; D008025:Ligases; D051379:Mice; D018345:Mice, Knockout; D009097:Multienzyme Complexes / Q000737:chemistry / Q000378:metabolism; D010447:Peptide Hydrolases / Q000737:chemistry / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex; D011506:Proteins / Q000378:metabolism*; D015398:Signal Transduction; D013379:Substrate Specificity; D025801:Ubiquitin / Q000737:chemistry / Q000378:metabolism*; D015003:Yeasts