An overlapping kinase and phosphatase docking site regulates activity of the retinoblastoma protein.Hirschi, A., Cecchini, M., Steinhardt, R.C., Schamber, M.R., Dick, F.A., Rubin, S.M.
(2010) Nat Struct Mol Biol 17: 1051-1057
- PubMed: 20694007
- DOI: https://doi.org/10.1038/nsmb.1868
- Primary Citation of Related Structures:
- PubMed Abstract:
The phosphorylation state and corresponding activity of the retinoblastoma tumor suppressor protein (Rb) are modulated by a balance of kinase and phosphatase activities. Here we characterize the association of Rb with the catalytic subunit of protein phosphatase 1 (PP1c). A crystal structure identifies an enzyme docking site in the Rb C-terminal domain that is required for efficient PP1c activity toward Rb. The phosphatase docking site overlaps with the known docking site for cyclin-dependent kinase (Cdk), and PP1 competition with Cdk-cyclins for Rb binding is sufficient to retain Rb activity and block cell-cycle advancement. These results provide the first detailed molecular insights into Rb activation and establish a novel mechanism for Rb regulation in which kinase and phosphatase compete for substrate docking.
Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, California, USA.