Heterodimeric Protein Kinases

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Heterodimeric Protein Kinases

• Presented By Becky Knight

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What makes up a heterodimeric Protein Kinases?

• Two different Subunits.
• Cyclin subunit regulatory subunit. Increases
  and decreases during cell cycle. Turns on kinase
  activity and they are degraded at certain points
  in cell cycle.
• Cyclin-dependant Kinase (Cdk) Catalytic
  subunit. No activity unless associated with a
  cyclin.

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There are different kinds of Cdks for each phase.

• G1 Cdk complex
• S-phase Cdk complex
• Mitotic Cdk complex

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G1 Cdk Complex

• Activated by the cell when it is ready to
  replicate.
• Begins breakdown of S-phase inhibitor and
  prepares cell for s-phase.
• Activates the enzymes that are required for gene
  encoding and DNA replication.

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S-phase Cdk Complex

• Regulates initiation of DNA replication.
• Ensures that the DNA is replicated only once.
• It begins to reactivate the s-phase inhibitor.

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Mitotic Cdk Complex

• Mitosis-promoting Factor (MPF)
• Released during the S-phase and G2 phase once DNA
  is replicated.
• Regulates mitosis by activating the breakdown
  of nuclear membrane, chromosome condensation,
  mitotic apparatus assembly, and chromosome
  alignment.
• Activates Anaphase-promoting Complex.

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Anaphase-promoting Complex

• Activated by MPF complex.
• Causes the reverse of mitosis.
• Allows for sister chromatid separation and
  segregation.
• Ends mitosis.

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Questions???