p53-dependent association between cyclin G and the B' subunit of protein phosphatase 2A.
We and others previously showed that cyclin G is a transcriptional target of the p53 tumor suppressor protein. However, cellular proteins which might form a complex with cyclin G have not yet been identified. To gain insight into the biological role of cyclin G, we used the yeast two-hybrid screen and isolated two mouse cDNAs encoding cyclin G-interacting proteins. Interestingly, both positive cDNAs encoded B' regulatory subunits of protein phosphatase 2A (PP2A). One clone encodes B'alpha, while the other clone codes for a new member of the B' family, B'beta. B'beta is 70% identical to other members of the B' family. B'alpha associated both in vitro and in vivo with cyclin G but not with the other mammalian cyclins. Furthermore, cyclin G formed a complex with B'alpha only after induction of p53 in p53 temperature-sensitive cell lines. These results indicate that cyclin G forms a specific complex with the B' subunit of PP2A and that complex formation is regulated by p53. Potential roles for the cyclin G-B' complex in p53-mediated pathways are discussed.
Howard Hughes Medical Institute, Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA.
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D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D016367:Baculoviridae; D019556:COS Cells; D002460:Cell Line; D003001:Cloning, Molecular; D056746:Cyclin G; D056766:Cyclin G1; D016213:Cyclins / Q000737:chemistry / Q000378:metabolism*; D046911:Macromolecular Substances; D008322:Mammals; D051379:Mice; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D054648:Protein Phosphatase 2; D017027:Protein Tyrosine Phosphatases / Q000737:chemistry / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000254:growth & development; D017386:Sequence Homology, Amino Acid; D018411:Spodoptera; D014162:Transfection; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
C534703:Ccng1 protein, mouse; D056746:Cyclin G; D056766:Cyclin G1; D016213:Cyclins; D046911:Macromolecular Substances; D011994:Recombinant Proteins; D016159:Tumor Suppressor Protein p53; D054648:Protein Phosphatase 2; D017027:Protein Tyrosine Phosphatases