Cic1, an adaptor protein specifically linking the 26S proteasome to its substrate, the SCF component Cdc4.
In eukaryotes, the ubiquitin-proteasome system plays a major role in selective protein breakdown for cellular regulation. Here we report the discovery of a new essential component of this degradation machinery. We found the Saccharomyces cerevisiae protein Cic1 attached to 26S proteasomes playing a crucial role in substrate specificity for proteasomal destruction. Whereas degradation of short-lived test proteins is not affected, cic1 mutants stabilize the F-box proteins Cdc4 and Grr1, substrate recognition subunits of the SCF complex. Cic1 interacts in vitro and in vivo with Cdc4, suggesting a function as a new kind of substrate recruiting factor or adaptor associated with the proteasome.
Jäger
S
S
Institut für Biochemie der Universität Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany.
Strayle
J
J
Heinemeyer
W
W
Wolf
D H
DH
D000595:Amino Acid Sequence; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000378:metabolism*; D044783:F-Box Proteins; D000073979:F-Box-WD Repeat-Containing Protein 7; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D010447:Peptide Hydrolases / Q000378:metabolism*; D010453:Peptide Synthases / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex; D044843:SKP Cullin F-Box Protein Ligases; D029701:Saccharomyces cerevisiae Proteins; D013379:Substrate Specificity; D044767:Ubiquitin-Protein Ligases; D014452:Ubiquitins
D002352:Carrier Proteins; D018797:Cell Cycle Proteins; C437314:Cic1 protein, S cerevisiae; D044783:F-Box Proteins; D000073979:F-Box-WD Repeat-Containing Protein 7; C513273:FBXW7 protein, human; D005656:Fungal Proteins; D029701:Saccharomyces cerevisiae Proteins; D014452:Ubiquitins; C071032:GRR1 protein, S cerevisiae; D044843:SKP Cullin F-Box Protein Ligases; D044767:Ubiquitin-Protein Ligases; D010447:Peptide Hydrolases; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease; D010453:Peptide Synthases