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Cdi1, a human G1 and S phase protein phosphatase that associates with Cdk2

J Gyuris1, E Golemis, H Chertkov

  • 1Department of Molecular Biology, Massachusetts General Hospital, Boston 02114.

Cell
|November 19, 1993
PubMed

Insights

We discovered cyclin-dependent kinase interactor 1 (Cdi1), a novel protein phosphatase that interacts with cyclin-dependent kinases. Cdi1

Area of Science:

  • Molecular Biology
  • Cell Cycle Regulation
  • Enzymology

Background:

  • Cyclin-dependent kinases (CDKs) are crucial regulators of the cell cycle.
  • Understanding CDK interactors is key to deciphering cell cycle control mechanisms.

Purpose of the Study:

  • To identify novel human proteins that interact with cyclin-dependent kinases.
  • To characterize the function and enzymatic activity of a newly identified CDK interactor.

Main Methods:

  • Utilized the yeast interaction trap, a genetic selection system, to isolate interacting proteins.
  • Performed biochemical assays to determine phosphatase activity and substrate specificity.
  • Investigated protein complex formation in human (HeLa) cells.
  • Conducted cell cycle progression studies in yeast and HeLa cells.

Main Results:

  • Identified human cyclin-dependent kinase interactor 1 (Cdi1) using the interaction trap.
  • Cdi1 interacts with several human CDKs (Cdc2, Cdk2, Cdk3) in yeast.
  • Cdi1 exhibits tyrosine phosphatase activity in vitro, confirmed by a catalytically inactive mutant.
  • Cdi1 forms stable complexes with Cdk2 in HeLa cells and is expressed during the G1 to S transition.
  • Overexpression of Cdi1 delays cell cycle progression in both yeast and HeLa cells, dependent on its phosphatase activity.

Conclusions:

  • Cdi1 is a novel protein phosphatase that complexes with cyclin-dependent kinases.
  • Cdi1's phosphatase activity plays a role in regulating cell cycle progression.
  • This discovery provides new insights into the intricate network of cell cycle control.

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