title: Interaction of NUB1 with the proteasome subunit S5a.
abstract: NUB1 interacts with a ubiquitin-like protein NEDD8 to target the NEDD8 monomer and neddylated proteins to the proteasome for degradation. Therefore, NUB1 is thought to be a potent downregulator of NEDD8 conjugation system. Since NUB1 possesses a UBL domain, which was previously shown to be an S5a-interacting motif in RAD23/HHR23, we initially hypothesized that NUB1 interacts with the S5a subunit of the proteasome through its UBL domain. To examine this, we performed an in vitro GST pull-down assay and a yeast two-hybrid assay. Unexpectedly, our studies revealed that NUB1 directly interacts with the S5a subunit through its C-terminal region between amino acid residues 536 and 584, not through its UBL domain. Although the UBL domain was not an S5a-interacting motif in NUB1, our further studies revealed that the UBL domain is required for the function of NUB1.
authors.affiliation: Department of Cardiology, The University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA.
authors.forename: Kunikazu
authors.initials: K
authors.lastname: Tanji
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Tanaka
authors.forename: Tetsu
authors.initials: T
authors.lastname: Kamitani
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D001665:Binding Sites; D019556:COS Cells; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002522:Chlorocebus aethiops; D006801:Humans; D046988:Proteasome Endopeptidase Complex; D017434:Protein Structure, Tertiary; D016601:RNA-Binding Proteins; D029701:Saccharomyces cerevisiae Proteins; D017384:Sequence Deletion; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020798:Two-Hybrid System Techniques
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; C430242:NUB1 protein, human; C498506:PSMD4 protein, human; D016601:RNA-Binding Proteins; C122019:RPN10 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D046988:Proteasome Endopeptidase Complex