Binding of HTm4 to cyclin-dependent kinase (Cdk)-associated phosphatase (KAP).Cdk2.cyclin A complex enhances the phosphatase activity of KAP, dissociates cyclin A, and facilitates KAP dephosphorylation of Cdk2

J Biol Chem. 2005 Apr 29;280(17):17235-42. doi: 10.1074/jbc.M413437200. Epub 2005 Jan 24.

Abstract

Cyclin-dependent kinase 2 (cdk2) activation requires phosphorylation of Thr160 and dissociation from cyclin A. The T-loop of cdk2 contains a regulatory phosphorylation site at Thr160. An interaction between cdc-associated phosphatase (KAP) and cdk2 compromises the interaction between cdk2 and cyclin A, which permits access of KAP, a Thr160-directed phosphatase, to its substrate, cdk2. We have reported that KAP is bound and activated by a nuclear membrane protein, HTm4. Here, we present in vitro data showing the direct interaction between the HTm4 C terminus and KAP Tyr141. We show that this interaction not only facilitates access of KAP to Thr160 and accelerates KAP kinetics, but also forces exclusion of cyclin A from the KAP.cdk2 complex.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Binding Sites
  • Blotting, Western
  • CDC2-CDC28 Kinases / chemistry
  • CDC2-CDC28 Kinases / metabolism*
  • Cell Cycle Proteins / chemistry*
  • Cell Cycle Proteins / metabolism*
  • Cell Nucleus / metabolism
  • Circular Dichroism
  • Cloning, Molecular
  • Cyclin A / chemistry
  • Cyclin A / metabolism*
  • Cyclin-Dependent Kinase 2
  • Cyclin-Dependent Kinase Inhibitor Proteins
  • Dose-Response Relationship, Drug
  • Dual-Specificity Phosphatases
  • Escherichia coli / metabolism
  • Humans
  • Ions
  • Kinetics
  • Membrane Proteins / chemistry*
  • Membrane Proteins / metabolism
  • Models, Biological
  • Models, Molecular
  • Molecular Sequence Data
  • Phosphorylation
  • Protein Binding
  • Protein Conformation
  • Protein Structure, Tertiary
  • Protein Tyrosine Phosphatases / chemistry
  • Protein Tyrosine Phosphatases / metabolism*
  • Recombinant Proteins / chemistry
  • Sequence Homology, Amino Acid
  • Threonine / chemistry
  • Time Factors
  • Tyrosine / chemistry

Substances

  • Cell Cycle Proteins
  • Cyclin A
  • Cyclin-Dependent Kinase Inhibitor Proteins
  • Ions
  • MS4A3 protein, human
  • Membrane Proteins
  • Recombinant Proteins
  • Threonine
  • Tyrosine
  • CDC2-CDC28 Kinases
  • CDK2 protein, human
  • Cyclin-Dependent Kinase 2
  • CDKN3 protein, human
  • Dual-Specificity Phosphatases
  • Protein Tyrosine Phosphatases