Related Experiment Video

Updated: Apr 19, 2026

Analysis of Cell Cycle Position in Mammalian Cells
12:19

Analysis of Cell Cycle Position in Mammalian Cells

Published on: January 21, 2012

61.7K

PP2A: more than a reset switch to activate pRB proteins during the cell cycle and in response to signaling cues

Alison Kurimchak1, Xavier Graña

  • 1a Fels Institute for Cancer Research and Molecular Biology and Department of Biochemistry; Temple University School of Medicine ; Philadelphia , PA USA.

Cell Cycle (Georgetown, Tex.)
|December 9, 2014
PubMed

Insights

Protein phosphatases PP2A and PP1 oppose cyclin-dependent kinases (CDKs) by dephosphorylating pocket proteins, regulating cell cycle progression. PP2A is highlighted for its role in integrating growth suppressor signals.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Pocket proteins (e.g., pRB) in hypophosphorylated state inhibit cell cycle by repressing E2F-dependent genes.
  • Cyclin-dependent kinases (CDKs) hyperphosphorylate and inactivate pocket proteins, releasing E2F repression.
  • Protein phosphatases PP2A and PP1 counteract CDK activity by dephosphorylating pocket proteins.

Purpose of the Study:

  • To review the role of protein phosphatase 2A (PP2A) in cell cycle regulation.
  • To highlight PP2A's function as a signaling hub for growth suppression.
  • To discuss the interplay between PP2A, PP1, CDKs, and pocket proteins.

Main Methods:

  • Literature review focusing on cell cycle regulation and protein phosphatases.
  • Analysis of the roles of PP2A and PP1 in pocket protein dephosphorylation.
  • Integration of findings on CDK and phosphatase activities in cell cycle control.

Main Results:

  • PP2A and PP1 oppose the cell cycle-promoting activity of CDKs on pocket proteins.
  • Specific PP2A holoenzymes are involved in dephosphorylating pocket proteins in response to cellular signals.
  • PP2A acts as a central integrator of growth suppressor pathways impacting pocket protein activity.

Conclusions:

  • PP2A plays a critical role in cell cycle regulation by inactivating pocket proteins.
  • Differential activation of PP2A holoenzymes leads to specific pocket protein inactivation.
  • Understanding PP2A function is key to comprehending cell cycle control and growth suppression mechanisms.
Keywords:
B55αB55δE2FPP2APPP2R2A PP1PR70cell cyclechondrocytep107p130pRBretinoblastoma

More Related Videos

Studying RNA Interactors of Protein Kinase RNA-Activated during the Mammalian Cell Cycle10:05

Studying RNA Interactors of Protein Kinase RNA-Activated during the Mammalian Cell Cycle

Published on: March 5, 2019

7.0K
Studying Cell Cycle-regulated Gene Expression by Two Complementary Cell Synchronization Protocols12:02

Studying Cell Cycle-regulated Gene Expression by Two Complementary Cell Synchronization Protocols

Published on: June 6, 2017

28.8K

Related Concept Videos

Negative Regulator Molecules01:23

Negative Regulator Molecules

Positive regulators allow a cell to advance through cell cycle checkpoints. Negative regulators have an equally important role as they terminate a cell’s progression through the cell cycle—or pause it—until the cell meets specific criteria.
39.2K
DNA Damage Can Stall the Cell Cycle02:36

DNA Damage Can Stall the Cell Cycle

In response to DNA damage, cells can pause the cell cycle to assess and repair the breaks. However, the cell must check the DNA at certain critical stages during the cell cycle. If the cell cycle pauses before DNA replication, the cells will contain twice the amount of DNA. On the other hand, if cells arrest after DNA replication but before mitosis, they will contain four times the normal amount of DNA. With a host of specialized proteins at their disposal,cells must use the right protein at...
3.4K
DNA Damage can Stall the Cell Cycle02:36

DNA Damage can Stall the Cell Cycle

In response to DNA damage, cells can pause the cell cycle to assess and repair the breaks. However, the cell must check the DNA at certain critical stages during the cell cycle. If the cell cycle pauses before DNA replication, the cells will contain twice the amount of DNA. On the other hand, if cells arrest after DNA replication but before mitosis, they will contain four times the normal amount of DNA. With a host of specialized proteins at their disposal,cells must use the right protein at...
10.4K
Abnormal Proliferation02:23

Abnormal Proliferation

Under normal conditions, most adult cells remain in a non-proliferative state unless stimulated by internal or external factors to replace lost cells. Abnormal cell proliferation is a condition in which the cell's growth exceeds and is uncoordinated with normal cells. In such situations, cell division persists in the same excessive manner even after cessation of the stimuli, leading to persistent tumors. The tumor arises from the damaged cells that replicate to pass the damage to the...
5.5K
Molecular Factors Affecting Cell Division01:27

Molecular Factors Affecting Cell Division

Several external and internal factors influence the initiation and inhibition of cell division. For instance, the death of nearby cells or the release of human growth hormone (hGH) promotes cell division. In contrast, lack of hGH or crowding of cells can inhibit cell division.
Several proteins function as internal regulators to ensure each cell cycle stage is completed faithfully before proceeding to the next. Regulator molecules may act directly or influence the activity or production of other...
4.1K
Mitogens and the Cell Cycle02:38

Mitogens and the Cell Cycle

Mitogens and their receptors play a crucial role in controlling the progression of the cell cycle. However, the loss of mitogenic control over cell division leads to tumor formation. Therefore, mitogens and mitogen receptors play an important role in cancer research. For instance, the epidermal growth factor (EGF) - a type of mitogen and its transmembrane receptor (EGFR), decides the fate of the cell's proliferation. When EGF binds to EGFR, a member of the ErbB family of tyrosine kinase...
8.5K