IMR Press / FBL / Volume 5 / Issue 3 / DOI: 10.2741/tamrakar

Frontiers in Bioscience-Landmark (FBL) is published by IMR Press from Volume 26 Issue 5 (2021). Previous articles were published by another publisher on a subscription basis, and they are hosted by IMR Press on as a courtesy and upon agreement with Frontiers in Bioscience.

Open Access Article
Role of pRB dephosphorylation in cell cycle regulation
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1 Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, New York 14642, USA
2 University of Rochester Cancer Center, Rochester, New York 14642, USA
Academic Editor:Norbert Berndt
Front. Biosci. (Landmark Ed) 2000, 5(3), 121–137;
Published: 1 January 2000
(This article belongs to the Special Issue Cellular functions of protein phosphatases)

pRB, the tumor suppressor product of the retinoblastoma susceptibility gene, is regarded as one of the key regulators of the cell cycle. This protein exerts its growth suppressive effect through its ability to bind and interact with a variety of cellular proteins. In turn, pRB binding and interacting ability is governed by its phosphorylation state. In recent years, this negative growth regulatory protein has captured a great deal of attention from investigators around the world due to its ability to modulate the activity of transcription regulatory proteins, enzymes which modify chromatin, and other cellular proteins which contribute to its complex role in mammalian cells. Hypophosphorylated pRB binds and sequesters transcription factors, most notably those of the E2F/DP family, inhibiting the transcription of genes required to traverse the G1 to S phase boundary. This cell cycle inhibitory function is abrogated when pRB undergoes phosphorylation mediated by cyclin/cdk complexes following cell stimulation by mitogens. Removal of these phosphates appears to be carried out by a multimeric complex of protein phosphatase type 1 (PP1) and noncatalytic regulatory subunits at the completion of mitosis. This dephosphorylation returns pRB to its active, growth suppressive state. While the mechanism of pRB phosphorylation has and continues to be extensively studied, dephosphorylation of pRB has received disproportionately less attention. The goal of this review is to revisit the role of pRB dephosphorylation in regulating the cell cycle. Emphasis will be placed on understanding the function and regulation of pRB during the cell cycle as well as our ever-expanding notions of pRB-PP1 interaction and the mechanism of pRB dephosphorylation at mitotic exit.

Serine/Threonine Protein Phosphatase
Protein Phosphatase Type 1 (PP1)
Cyclin-Dependent Kinase Activity
Mammalian Cell Cycle
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