title: CK2 phosphorylation of human Sec63 regulates its interaction with Sec62.
abstract: BACKGROUND
  Protein kinase CK2 is a pleiotropic enzyme which is ubiquitously expressed in eukaryotic cells. Several years ago CK2 was found to be associated with the mammalian endoplasmic reticulum. So far nothing is known about the function of CK2 at the ER.
  
  
  METHODS
  CK2 phosphorylation sites in the polypeptide chain of Sec63 were mapped using deletion mutants and a peptide library. Binding of Sec63 to CK2 and to Sec62 was analyzed by pull-down assays and by co-immunoprecipitation
  
  
  RESULTS
  Sec63 was identified as a novel substrate and binding partner of protein kinase CK2. We identified serine 574, serine 576 and serine 748 as CK2 phosphorylation sites. Phosphorylation of Sec63 by CK2 enhanced its binding to Sec62.
  
  
  CONCLUSIONS
  Protein kinase CK2 phosphorylation of Sec63 leads to an enhanced binding of Sec63 to Sec62. This complex formation is a prerequisite for a functional ER protein translocon.
  
  
  CONCLUSIONS
  Thus, our present data indicate a regulatory role of CK2 in the ER protein translocation.
authors.affiliation: Medizinische Biochemie und Molekularbiologie und Kompetenzzentrum Molekulare Medizin, Universität des Saarlandes, Gebäude 44, 66424 Homburg, Germany.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Ampofo
authors.forename: Sabrina
authors.initials: S
authors.lastname: Welker
authors.forename: Martin
authors.initials: M
authors.lastname: Jung
authors.forename: Linda
authors.initials: L
authors.lastname: Müller
authors.forename: Markus
authors.initials: M
authors.lastname: Greiner
authors.forename: Richard
authors.initials: R
authors.lastname: Zimmermann
authors.forename: Mathias
authors.initials: M
authors.lastname: Montenarh
mesh_terms: D000595:Amino Acid Sequence; D047390:Casein Kinase II / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism; D056945:Hep G2 Cells; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry*; D026901:Membrane Transport Proteins / Q000737:chemistry*; D018832:Molecular Chaperones; D008969:Molecular Sequence Data; D010766:Phosphorylation; D016601:RNA-Binding Proteins
chemical_list: D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D018832:Molecular Chaperones; D016601:RNA-Binding Proteins; C103676:SEC62 protein, human; C487464:SEC63 protein, human; D047390:Casein Kinase II