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14-3-3 proteins interact with specific MEK kinases

G R Fanger1, C Widmann, A C Porter

  • 1Program in Molecular Signal Transduction, Division of Basic Sciences, National Jewish Medical and Research Center, Denver, Colorado 80206, USA.

The Journal of Biological Chemistry
|March 7, 1998
PubMed

Insights

14-3-3 proteins act as scaffolds, binding MEK kinases (MEKKs) and influencing protein interactions. Caspase-3 cleavage of MEKK1 alters these interactions, affecting kinase signaling pathways.

Area of Science:

  • Molecular Biology
  • Cell Signaling
  • Protein Kinase Research

Background:

  • Mitogen-activated protein kinase (MAPK) kinases, known as MEKKs, are crucial regulators of cellular signaling pathways.
  • 14-3-3 proteins are known to interact with various signaling molecules, influencing their function.

Purpose of the Study:

  • To investigate the interaction between 14-3-3 proteins and MEKK family members.
  • To elucidate the functional consequences of these interactions, particularly in relation to MEKK1 cleavage by caspase-3.

Main Methods:

  • Yeast two-hybrid screening to identify interacting proteins.
  • In vitro binding assays to determine binding affinity and domains.
  • Cellular localization studies using immunofluorescence.
  • Analysis of caspase-3 cleavage on MEKK1 and subsequent protein interactions.

Main Results:

  • 14-3-3 proteins (zeta and epsilon) bind to both N-terminal regulatory and C-terminal kinase domains of MEKK3 with high affinity.
  • Interactions were observed with MEKK1 and MEKK2, but not MEKK4.
  • Caspase-3 cleavage of MEKK1 releases the kinase domain from the 14-3-3 binding region, altering protein interactions.
  • 14-3-3 proteins primarily function as scaffolds for MEKK1, MEKK2, and MEKK3, rather than directly modulating their activity.

Conclusions:

  • 14-3-3 proteins serve as critical scaffolds in MEKK signaling pathways.
  • Caspase-3 mediated cleavage of MEKK1 represents a mechanism to regulate protein kinase interactions.
  • These findings highlight a novel regulatory mechanism controlling kinase signaling through protein-protein interactions and post-translational modification.

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