Abstract
Protein kinase CK2 is a ubiquitous and pleiotropic Ser/Thr protein kinase involved in cell growth and transformation. Here we report the identification by yeast interaction trap of a CK2 interacting protein, UBC3B, which is highly homologous to the E2 ubiquitin conjugating enzyme UBC3/CDC34. UBC3B complements the yeast cdc34-2 cell cycle arrest mutant in S. cerevisiae and transfers ubiquitin to a target substrate in vitro. UBC3B is specifically phosphorylated by CK2 in vitro and in vivo. We mapped by deletions and site directed mutagenesis the phosphorylation site to a serine residue within the C-terminal domain in position 233 of UBC3B and in the corresponding serine residue of UBC3. Following CK2-dependent phosphorylation both UBC3B and UBC3 bind to the F-box protein beta-TrCP, the substrate recognition subunit of an SCF (Skp1, Cul1, F-box) ubiquitin ligase. Furthermore, we observed that co-transfection of CK2alpha' together with UBC3B, but not with UBC3DeltaC, enhances the degradation of beta-catenin. Taken together these data suggest that CK2-dependent phosphorylation of UBC3 and UBC3B functions by regulating beta-TrCP substrate recognition.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Anaphase-Promoting Complex-Cyclosome
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Animals
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Casein Kinase II
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Cells, Cultured
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Chloramphenicol O-Acetyltransferase / metabolism
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Cloning, Molecular
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Cytoskeletal Proteins / metabolism*
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DNA Primers / chemistry
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GTP-Binding Proteins / metabolism*
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Gene Library
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Genetic Complementation Test
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Glutathione Transferase / metabolism
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Humans
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Ligases / genetics
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Ligases / metabolism*
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Mice
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Molecular Sequence Data
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Phosphorylation
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Plasmids
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Polymerase Chain Reaction
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Precipitin Tests
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Promoter Regions, Genetic
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Protein Serine-Threonine Kinases / metabolism*
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Saccharomyces cerevisiae
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Saccharomyces cerevisiae Proteins
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Sequence Homology, Amino Acid
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Trans-Activators*
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Ubiquitin / metabolism
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Ubiquitin-Conjugating Enzymes
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Ubiquitin-Protein Ligase Complexes*
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beta Catenin
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beta-Transducin Repeat-Containing Proteins
Substances
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BTRC protein, human
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Btrc protein, mouse
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CTNNB1 protein, human
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CTNNB1 protein, mouse
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Cytoskeletal Proteins
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DNA Primers
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Saccharomyces cerevisiae Proteins
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Trans-Activators
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Ubiquitin
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beta Catenin
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beta-Transducin Repeat-Containing Proteins
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Chloramphenicol O-Acetyltransferase
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CDC34 protein, S cerevisiae
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CDC34 protein, human
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Ube2r2 protein, mouse
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Ubiquitin-Conjugating Enzymes
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Ubiquitin-Protein Ligase Complexes
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Anaphase-Promoting Complex-Cyclosome
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Glutathione Transferase
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Casein Kinase II
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Protein Serine-Threonine Kinases
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GTP-Binding Proteins
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Ligases
Associated data
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GENBANK/AJ240086
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GENBANK/AJ240087