PR48, a novel regulatory subunit of protein phosphatase 2A, interacts with Cdc6 and modulates DNA replication in human cells.
Initiation of DNA replication in eukaryotes is dependent on the activity of protein phosphatase 2A (PP2A), but specific phosphoprotein substrates pertinent to this requirement have not been identified. A novel regulatory subunit of PP2A, termed PR48, was identified by a yeast two-hybrid screen of a human placental cDNA library, using human Cdc6, an essential component of prereplicative complexes, as bait. PR48 binds specifically to an amino-terminal segment of Cdc6 and forms functional holoenzyme complexes with A and C subunits of PP2A. PR48 localizes to the nucleus of mammalian cells, and its forced overexpression perturbs cell cycle progression, causing a G(1) arrest. These results suggest that dephosphorylation of Cdc6 by PP2A, mediated by a specific interaction with PR48, is a regulatory event controlling initiation of DNA replication in mammalian cells.
Yan
Z
Z
Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA.
Fedorov
S A
SA
Mumby
M C
MC
Williams
R S
RS
D000595:Amino Acid Sequence; D000818:Animals; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002460:Cell Line; D003001:Cloning, Molecular; D004261:DNA Replication; D005260:Female; D015723:Gene Library; D006367:HeLa Cells; D006801:Humans; D046911:Macromolecular Substances; D051379:Mice; D008969:Molecular Sequence Data; D010749:Phosphoprotein Phosphatases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010802:Phylogeny; D010920:Placenta / Q000201:enzymology; D011247:Pregnancy; D054648:Protein Phosphatase 2; D020836:Protein Structure, Quaternary; D011817:Rabbits; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development; D029701:Saccharomyces cerevisiae Proteins; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D018411:Spodoptera; D014162:Transfection
C066503:CDC6 protein, S cerevisiae; D018797:Cell Cycle Proteins; D046911:Macromolecular Substances; C403618:PPP2R3B protein, human; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D010749:Phosphoprotein Phosphatases; D054648:Protein Phosphatase 2