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Updated: Jul 15, 2025

Defining Substrate Specificities for Lipase and Phospholipase Candidates
Published on: November 23, 2016
Redox Modification of PKA-Cα Differentially Affects Its Substrate Selection
Jeannette Delva-Wiley1, Ese S Ekhator1, Laquaundra L Adams1
1Department of Biology, North Carolina A&T State University, Greensboro, NC 27411, USA.
Redox modification of cyclic AMP-dependent protein kinase alpha (PKA-Cα) alters its substrate specificity. Oxidation impacts PKA-Cα activity differently across various substrates, revealing crosstalk between redox and phosphorylation signaling.
Area of Science:
- Biochemistry
- Cellular Signaling
- Enzymology
Background:
- Cyclic AMP-dependent protein kinase (PKA) regulates crucial cellular processes and is implicated in diseases like diabetes and neurodegeneration.
- The alpha isoform of the catalytic subunit of PKA (PKA-Cα) undergoes oxidation at C199, located in the active site.
- The functional impact of PKA-Cα C199 oxidation on substrate selection is largely unknown.
Purpose of the Study:
- To investigate how redox modification of PKA-Cα at C199 affects its substrate specificity.
- To explore the differential effects of oxidation on PKA-Cα's kinase activity towards various substrates.
- To understand the interplay between redox and phosphorylation signaling pathways mediated by PKA.
Main Methods:
- Biochemical assays including trans-phosphorylation and steady-state kinetics.
- Biophysical techniques such as surface plasmon resonance and fluorescence polarization.
- Examined the effects of diamide- and H2O2-induced oxidation on PKA-Cα activity.
Main Results:
- Redox modification of PKA-Cα differentially impacts its activity towards different substrates.
- Diamide-mediated oxidation reduced PKA-Cα activity on Kemptide and CREBtide but not Crosstide.
- H2O2-dependent oxidation initially increased PKA-Cα activity across substrates, with concentration-dependent variations.
Conclusions:
- Oxidation of PKA-Cα at C199 alters substrate selection, highlighting crosstalk between redox and phosphorylation signaling.
- Findings provide insights into the role of PKA in integrating redox and phosphorylation signals.
- The conserved nature of C199 suggests broader implications for AGC kinase family members in redox-dependent signaling.
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