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Development of Inhibitors of Protein-protein Interactions through REPLACE: Application to the Design and Development Non-ATP Competitive CDK Inhibitors
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Purification, characterization, and kinetic mechanism of cyclin D1. CDK4, a major target for cell cycle regulation

A K Konstantinidis1, R Radhakrishnan, F Gu

  • 1Research Technologies and Proteins, Lilly Research Laboratories, Division of Eli Lilly and Company, Indianapolis, Indiana 46285, USA.

The Journal of Biological Chemistry
|October 3, 1998
PubMed

Insights

Researchers purified the cyclin D1.CDK4 complex, a key cell cycle regulator implicated in cancer. They characterized its kinase activity and mechanism, validating it for antiproliferative drug discovery.

Area of Science:

  • Biochemistry
  • Molecular Biology
  • Cancer Research

Background:

  • The cyclin D1.CDK4-pRb pathway is crucial for cell cycle progression.
  • Deregulation of this pathway is linked to various cancers, making it a significant drug target.

Purpose of the Study:

  • To purify and characterize the cyclin D1.CDK4 complex for drug discovery.
  • To elucidate the kinetic mechanism and catalytic properties of the kinase complex.

Main Methods:

  • Purification of dimeric cyclin D1.CDK4 complex and a cyclin D1-CDK4 fusion protein using recombinant baculovirus expression.
  • Optimization of kinase activity and stability.
  • Kinetic analysis using steady-state kinetics with peptide (RbING) and protein (Rb21) phosphoacceptors.
  • Inhibition studies with staurosporine and ADP.
  • Molecular modeling of staurosporine in the ATP-binding site.

Main Results:

  • Successfully purified active dimeric cyclin D1.CDK4 complex and a fusion protein.
  • Determined a "single displacement or Bi-Bi" kinetic mechanism for the complex.
  • Observed significantly tighter ATP binding with Rb21 compared to RbING.
  • Modeled staurosporine binding within the CDK4 ATP-binding site.

Conclusions:

  • The purified cyclin D1.CDK4 complex and fusion protein are validated as active kinases.
  • These preparations are suitable for screening and discovering antiproliferative inhibitors targeting the cyclin D1.CDK4 pathway.

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