title: Protein interaction screening for the ankyrin repeats and suppressor of cytokine signaling (SOCS) box (ASB) family identify Asb11 as a novel endoplasmic reticulum resident ubiquitin ligase.
abstract: The ankyrin and SOCS (suppressor of cytokine signaling) box (ASB) family of proteins function as the substrate recognition subunit in a subset of Elongin-Cullin-SOCS (ECS) E3 ubiquitin ligases. Despite counting 18 members in humans, the identity of the physiological targets of the Asb proteins remains largely unexplored. To increase our understanding of the function of ASB proteins, we conducted a family-wide SILAC (stable isotope labeling by amino acids in cell culture)-based protein/protein interaction analysis. This investigation led to the identification of novel as well as known ASB-associated proteins like Cullin 5 and Elongins B/C. We observed that several proteins can be bound by more than one Asb protein. The additional exploration of this phenomenon demonstrated that ASB-Cullin 5 complexes can oligomerize and provides evidence that Cullin 5 forms heterodimeric complexes with the Cullin 4a-DDB1 complex. We also demonstrated that ASB11 is a novel endoplasmic reticulum-associated ubiquitin ligase with the ability to interact and promote the ubiquitination of Ribophorin 1, an integral protein of the oligosaccharyltransferase (OST) glycosylation complex. Moreover, expression of ASB11 can increase Ribophorin 1 protein turnover in vivo. In summary, we provide a comprehensive protein/protein interaction data resource that can aid the biological and functional characterization of ASB ubiquitin ligases.
authors: From the Departments of Disease Biology.
authors: Christina Aaen
authors: CA
authors: Andresen
authors: Stine
authors: S
authors: Smedegaard
authors: Kathrine Beck
authors: KB
authors: Sylvestersen
authors: Charlotte
authors: C
authors: Svensson
authors: Diego
authors: D
authors: Iglesias-Gato
authors: Giuseppe
authors: G
authors: Cazzamali
authors: Tine Kragh
authors: TK
authors: Nielsen
authors: Michael Lund
authors: ML
authors: Nielsen
authors: Amilcar
authors: A
authors: Flores-Morales
mesh_terms: D044842:Cullin Proteins / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000201:enzymology* / Q000235:genetics; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D009097:Multienzyme Complexes / Q000235:genetics / Q000378:metabolism*; D050826:Suppressor of Cytokine Signaling Proteins / Q000235:genetics / Q000378:metabolism*; D054875:Ubiquitination / Q000502:physiology*
chemical_list: C496871:CUL5 protein, human; D044842:Cullin Proteins; C091435:DDB1 protein, human; D004268:DNA-Binding Proteins; D008565:Membrane Proteins; D009097:Multienzyme Complexes; D050826:Suppressor of Cytokine Signaling Proteins; C034241:ribophorin
keywords: Endoplasmic Reticulum (ER); Glycation; Mass Spectrometry (MS); Proteomics; Ubiquitin Ligase; Ubiquitylation