Cic1, an adaptor protein specifically linking the 26S proteasome to its substrate, the SCF component Cdc4

• Published in: The EMBO journal Vol. 20; no. 16; pp. 4423 - 4431
• Main Authors: Jäger, Sibylle, Strayle, Jochen, Heinemeyer, Wolfgang, Wolf, Dieter H.
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 15.08.2001; Blackwell Publishing Ltd; Oxford University Press
• Subjects: Amino Acid Sequence; Carrier Proteins - genetics; Carrier Proteins - metabolism; Cdc gene; Cdc4; Cdc4 protein; Cell Cycle Proteins - metabolism; Cic1; Cic1 gene; Cic1 protein; F-Box Proteins; F-Box-WD Repeat-Containing Protein 7; Fungal Proteins - genetics; Fungal Proteins - metabolism; Grr1 protein; Humans; Molecular Sequence Data; Peptide Hydrolases - metabolism; Peptide Synthases - metabolism; proteasome; proteasome 26S; Proteasome Endopeptidase Complex; protein degradation; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins; SCF; SKP Cullin F-Box Protein Ligases; Substrate Specificity; Ubiquitin-Protein Ligases; Ubiquitins
• ISSN: 0261-4189; 1460-2075; 1460-2075
• DOI: 10.1093/emboj/20.16.4423

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.