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p42 MAPK phosphorylates 80 kDa MARCKS at Ser-113
D C Schönwasser1, R H Palmer, T Herget
1Protein Phosphorylation Laboratory, Imperial Cancer Research Fund, London, UK.
FEBS Letters
|October 14, 1996
Summary
p42 MAPKinase (MAPK) phosphorylates Myristoylated Alanine-Rich C-Kinase Substrate (MARCKS) at Ser-113 in vitro. However, its phosphorylation is not acutely regulated by p42 MAPK in Swiss 3T3 cells.
Area of Science:
- Cellular signaling pathways
- Protein phosphorylation
- Signal transduction
Background:
- Myristoylated Alanine-Rich C-Kinase Substrate (MARCKS) is a key substrate in cellular signaling.
- p42 MAPKinase (MAPK) is a critical enzyme in mitogenic signaling pathways.
- Regulation of MARCKS phosphorylation by MAPK is not fully understood.
Purpose of the Study:
- To investigate the phosphorylation of MARCKS at Ser-113 by p42 MAPK.
- To determine if p42 MAPK acutely regulates MARCKS phosphorylation at Ser-113 in Swiss 3T3 cells.
Main Methods:
- In vitro kinase assays using p42 MAPK and MARCKS.
- Analysis of MARCKS phosphorylation in permeabilized Swiss 3T3 cells stimulated with platelet-derived growth factor (PDGF) or activated protein kinase C (PKC).
Main Results:
- p42 MAPK directly phosphorylates MARCKS at Ser-113 in vitro.
- Activation of PKC or PDGF stimulation in Swiss 3T3 cells leads to p42 MAPK activation.
- Despite p42 MAPK activation, only PKC sites on MARCKS are phosphorylated, not Ser-113.
Conclusions:
- Ser-113 of MARCKS is a substrate for p42 MAPK.
- Acute regulation of MARCKS Ser-113 phosphorylation by p42 MAPK does not occur in Swiss 3T3 cells under the tested conditions.