Protein kinase C in rat brain myelin
T Yoshimura1, T Kobayashi, I Goto
1Department of Neurology, Faculty of Medicine, Kyushu University, Fukuoka, Japan.
Neurochemical Research
|October 1, 1992
Summary
Protein kinase C (PKC) in rat central nervous system (CNS) myelin phosphorylates myelin basic protein (MBP) on serine residues. This PKC activity, involving isoforms II and III, parallels myelin protein deposition during development.
Area of Science:
- Neuroscience
- Biochemistry
- Cell Biology
Background:
- Myelin basic protein (MBP) phosphorylation is crucial for CNS function.
- Protein kinase C (PKC) is a candidate enzyme for MBP phosphorylation in myelin.
Purpose of the Study:
- To demonstrate that PKC directly phosphorylates MBP within CNS myelin.
- To identify the specific PKC isoforms present in myelin and their role in MBP phosphorylation.
Main Methods:
- Partial purification of PKC from rat CNS myelin using Triton X-100 and DEAE-cellulose chromatography.
- In vitro phosphorylation assays using MBP and histone III-S as substrates.
- High-voltage electrophoresis to identify phosphoamino acids.
- SDS-PAGE, Western blotting with anti-PKC antibodies to confirm PKC presence and isoforms.
- Developmental analysis of PKC activity in myelin.
Main Results:
- Rat myelin PKC phosphorylated MBP and histone III-S, with serine identified as the phosphoamino acid.
- PKC activity was inhibited by psychosine.
- Rat CNS myelin contained intact PKC (approx. 80 kDa) and PKC isoforms II and III.
- Myelin PKC activity correlated with myelin protein deposition from postnatal days 14 to 42.
Conclusions:
- PKC is present in CNS myelin and directly phosphorylates MBP.
- PKC isoforms II and III are the predominant forms in myelin.
- Myelin-associated PKC activity is developmentally regulated and linked to myelination.
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