title: Human ASPL/TUG interacts with p97 and complements the proteasome mislocalization of a yeast ubx4 mutant, but not the ER-associated degradation defect.
abstract: BACKGROUND
  In mammalian cells, ASPL is involved in insulin-stimulated redistribution of the glucose transporter GLUT4 and assembly of the Golgi apparatus. Its putative yeast orthologue, Ubx4, is important for proteasome localization, endoplasmic reticulum-associated protein degradation (ERAD), and UV-induced degradation of RNA polymerase.
  
  
  RESULTS
  Here, we show that ASPL is a cofactor of the hexameric ATPase complex, known as p97 or VCP in mammals and Cdc48 in yeast. In addition, ASPL interacts in vitro with NSF, another hexameric ATPase complex. ASPL localizes to the ER membrane. The central area in ASPL, containing both a SHP box and a UBX domain, is required for binding to the p97 N-domain. Knock-down of ASPL does not impair degradation of misfolded secretory proteins via the ERAD pathway. Deletion of UBX4 in yeast causes cycloheximide sensitivity, while ubx4 cdc48-3 double mutations cause proteasome mislocalization. ASPL alleviates these defects, but not the impaired ERAD.
  
  
  CONCLUSIONS
  In conclusion, ASPL and Ubx4 are homologous proteins with only partially overlapping functions. Both interact with p97/Cdc48, but while Ubx4 is important for ERAD, ASPL appears not to share this function.
authors: Louise
authors: L
authors: Madsen
authors: Karen
authors: K
authors: Molbæk
authors: Ida B
authors: IB
authors: Larsen
authors: Sofie V
authors: SV
authors: Nielsen
authors: Esben G
authors: EG
authors: Poulsen
authors: Peter S
authors: PS
authors: Walmod
authors: Kay
authors: K
authors: Hofmann
authors: Michael
authors: M
authors: Seeger
authors: Chen-Ying
authors: CY
authors: Chien
authors: Rey-Huei
authors: RH
authors: Chen
authors: Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, Copenhagen N DK-2200, Denmark. fkriegenburg@bio.ku.dk.
authors: Franziska
authors: F
authors: Kriegenburg
authors: Rasmus
authors: R
authors: Hartmann-Petersen
mesh_terms: D000251:Adenosine Triphosphatases / Q000032:analysis / Q000378:metabolism*; D002352:Carrier Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D060746:Endoplasmic Reticulum-Associated Degradation; D017353:Gene Deletion; D055786:Gene Knockout Techniques; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D009154:Mutation; D009687:Nuclear Proteins / Q000032:analysis / Q000378:metabolism*; D015514:Oncogene Proteins, Fusion / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex / Q000032:analysis / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*
chemical_list: C422743:ASPSCR1 protein, human; D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; D009687:Nuclear Proteins; D015514:Oncogene Proteins, Fusion; D029701:Saccharomyces cerevisiae Proteins; C542871:UBX4 protein, S cerevisiae; D046988:Proteasome Endopeptidase Complex; D000251:Adenosine Triphosphatases; C404942:p97 ATPase