title: GFP-labelling of 26S proteasomes in living yeast: insight into proteasomal functions at the nuclear envelope/rough ER.
abstract: 26S proteasomes are multisubunit protease complexes that play the central role in the ubiquitin-dependent protein degradation pathway. The proteolytically active core is formed by the 20S proteasome. Regulatory subunits, principally the 19S cap complex, confer the specificity towards ubiquitinated substrates and an ATP-dependence on proteolysis. Green fluorescence protein (GFP)-tagged versions of either an alpha-subunit of the 20S core or an ATPase subunit of the 19S cap complex were functionally incorporated into the protease complex, thus allowing to monitor the subcellular distribution of 26S proteasomes in living yeast. Our localization studies suggest that proteasomal proteolysis mainly occurs at the nuclear envelope (NE)/rough ER. Implications of proteasomal functions at the NE/rough ER are discussed in the context of published work on ER degradation and with regard to possible targeting mechanisms.
authors.affiliation: Institut für Biochemie, Humboldt Universität, Universitätsklinikum Charité, Berlin, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Enenkel
authors.forename: A
authors.initials: A
authors.lastname: Lehmann
authors.forename: P M
authors.initials: PM
authors.lastname: Kloetzel
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D018870:Endoplasmic Reticulum, Rough / Q000201:enzymology*; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins / Q000378:metabolism; D009685:Nuclear Envelope / Q000201:enzymology*; D010447:Peptide Hydrolases / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D015003:Yeasts / Q000201:enzymology*
chemical_list: D008164:Luminescent Proteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D000255:Adenosine Triphosphate; D010447:Peptide Hydrolases; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease; D000251:Adenosine Triphosphatases