Cyclin D:Cdk4/6 Activates Rb in Early G1 Phase by Mono-Phosphorylation

ABSTRACT: The retinoblastoma tumor suppressor protein (Rb) regulates early G1 phase checkpoints, including the DNA damage response, as well as cell cycle exit and differentiation. The widely accepted model of G1 cell cycle progression proposes that cyclin D:Cdk4/6 partially inactivates the Rb tumor suppressor during early G1 phase by progressive multi-phosphorylation, termed hypo-phosphorylation, resulting in release of E2F transcription factors. However, this model remains largely unproven biochemically and the biologically active form(s) of Rb remains unknown. Here we find that Rb is un-phosphorylated in G0 cells and becomes exclusively mono-phosphorylated throughout all of early G1 phase by cyclin D:Cdk4/6. Early G1 phase mono-phosphorylated Rb is composed of 14 independent isoforms that are

ORGANISM(S): Mus musculus

SUBMITTER: Steven Dowdy 

PROVIDER: E-GEOD-56453 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress