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Updated: Dec 9, 2025

Identification of Cyclin-dependent Kinase 1 Specific Phosphorylation Sites by an In Vitro Kinase Assay
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Identification of Cyclin-dependent Kinase 1 Specific Phosphorylation Sites by an In Vitro Kinase Assay

Published on: May 3, 2018

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CaMKK2 is inactivated by cAMP-PKA signaling and 14-3-3 adaptor proteins

Christopher G Langendorf1, Matthew T O'Brien1, Kevin R W Ngoei1

  • 1St Vincent's Institute and Department of Medicine, University of Melbourne, Fitzroy, Australia.

The Journal of Biological Chemistry
|September 11, 2020
PubMed

Insights

Cyclic AMP-dependent protein kinase A (PKA) inactivates calcium-calmodulin-dependent protein kinase kinase-2 (CaMKK2) through phosphorylation. This PKA-mediated CaMKK2 inactivation offers a potential therapeutic strategy for various diseases.

Area of Science:

  • Biochemistry
  • Molecular Biology
  • Cell Signaling

Background:

  • Calcium-calmodulin-dependent protein kinase kinase-2 (CaMKK2) regulates energy metabolism and is implicated in diseases like cancer and metabolic disorders.
  • While CaMKK2 activation is understood, its inactivation mechanisms remain unclear, hindering therapeutic development.

Purpose of the Study:

  • To elucidate the intracellular mechanisms responsible for CaMKK2 inactivation.
  • To identify potential therapeutic targets for CaMKK2 inhibition.

Main Methods:

  • Investigated the role of cAMP-dependent protein kinase A (PKA) signaling in CaMKK2 inactivation.
  • Utilized phosphorylation site analysis and structural biology (crystal structure of 14-3-3ζ bound to a peptide).

Main Results:

  • Demonstrated that PKA inactivates CaMKK2 by phosphorylating three serine residues (Ser495, Ser100, Ser511).
  • Phosphorylation of Ser495 directly inhibits CaMKK2 activation by calcium-calmodulin.
  • Phosphorylation of Ser100 and Ser511 recruits 14-3-3 proteins, stabilizing the inactive state by preventing phospho-Ser495 dephosphorylation.
  • Crystal structure revealed how canonical and noncanonical 14-3-3 binding sites on CaMKK2 cooperate.

Conclusions:

  • Detailed molecular insights into cAMP-PKA-mediated CaMKK2 inactivation pathway.
  • Identified a novel mechanism for inhibiting CaMKK2, offering potential therapeutic applications for cancer and metabolic diseases.
Keywords:
14-3-314-3-3 proteinCa2+Ca2+-calmodulin–dependent protein kinase (CaMK)Ca2+-calmodulin–dependent protein kinase kinase-2 (CaMKK2)CaMKK2PKAadaptor proteincAMPcalmodulincalmodulin (CaM)cyclic AMP (cAMP)inhibition mechanismprotein kinase A (PKA)

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