title: Functional consequences of necdin nucleocytoplasmic localization.
abstract: BACKGROUND
  Necdin, a MAGE family protein expressed primarily in the nervous system, has been shown to interact with both nuclear and cytoplasmic proteins, but the mechanism of its nucleocytoplasmic transport are unknown.
  
  
  RESULTS
  We carried out a large-scale interaction screen using necdin as a bait in the yeast RRS system, and found a wide range of potential interactors with different subcellular localizations, including over 60 new candidates for direct binding to necdin. Integration of these interactions into a comprehensive network revealed a number of coherent interaction modules, including a cytoplasmic module connecting to necdin through huntingtin-associated protein 1 (Hap1), dynactin and hip-1 protein interactor (Hippi); a nuclear P53 and Creb-binding-protein (Crebbp) module, connecting through Crebbp and WW domain-containing transcription regulator protein 1 (Wwtr1); and a nucleocytoplasmic transport module, connecting through transportins 1 and 2. We validated the necdin-transportin1 interaction and characterized a sequence motif in necdin that modulates karyopherin interaction. Surprisingly, a D234P necdin mutant showed enhanced binding to both transportin1 and importin β1. Finally, exclusion of necdin from the nucleus triggered extensive cell death.
  
  
  CONCLUSIONS
  These data suggest that necdin has multiple roles within protein complexes in different subcellular compartments, and indicate that it can utilize multiple karyopherin-dependent pathways to modulate its localization.
authors.affiliation: Department of Biological Chemistry, Weizmann Institute of Science, Rehovot, Israel.
authors.forename: Anat
authors.initials: A
authors.lastname: Lavi-Itzkovitz
authors.forename: Marianna
authors.initials: M
authors.lastname: Tcherpakov
authors.forename: Zehava
authors.initials: Z
authors.lastname: Levy
authors.forename: Shalev
authors.initials: S
authors.lastname: Itzkovitz
authors.forename: Francoise
authors.initials: F
authors.lastname: Muscatelli
authors.forename: Mike
authors.initials: M
authors.lastname: Fainzilber
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000502:physiology; D020816:Amino Acid Motifs; D000818:Animals; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism*; D003593:Cytoplasm / Q000235:genetics / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D051379:Mice; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D016716:PC12 Cells; D011485:Protein Binding / Q000502:physiology; D051381:Rats
chemical_list: D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; C069766:necdin