Yeast ubiquitin-conjugating enzymes involved in selective protein degradation are essential for cell viability.
Ubiquitin-mediated proteolysis is a major pathway for selective protein degradation in eukaryotic cells. This proteolysis pathway involves the processive covalent attachment of ubiquitin to proteolytic substrates and their subsequent degradation by a specific ATP-dependent protease complex. We have cloned the genes and characterized the function of ubiquitin-conjugating enzymes (UBCs) from the yeast Saccharomyces cerevisiae. UBC1, UBC4 and UBC5 enzymes were found to mediate selective degradation of short-lived and abnormal proteins. These enzymes have overlapping functions and constitute a UBC subfamily essential for growth. UBC1 is specifically required at early stages of growth after germination of spores. UBC4 and UBC5 enzymes generate high molecular weight ubiquitin-protein conjugates and comprise a major ubiquitin-conjugation activity in yeast cells. Moreover, these enzymes are central components of the cellular stress response.
Seufert
W
W
Friedrich-Miescher-Laboratorium der Max-Planck-Gesellschaft, Tübingen, FRG.
Jentsch
S
S
D000595:Amino Acid Sequence; D006360:Heat-Shock Proteins / Q000378:metabolism; D006358:Hot Temperature / Q000009:adverse effects; D008025:Ligases / Q000235:genetics / Q000502:physiology*; D008969:Molecular Sequence Data; D010641:Phenotype; D011489:Protein Denaturation; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D029701:Saccharomyces cerevisiae Proteins; D044763:Ubiquitin-Conjugating Enzymes
D006360:Heat-Shock Proteins; D029701:Saccharomyces cerevisiae Proteins; C066752:UBC1 protein, S cerevisiae; C489270:UBC5 protein, S cerevisiae; D044763:Ubiquitin-Conjugating Enzymes; C063109:ubiquitin-conjugating enzyme UBC4; D008025:Ligases