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[Studies on polyamine-dependent protein kinase in pig epidermal cells]
[Hokkaido Igaku Zasshi] the Hokkaido Journal of Medical Science
|January 1, 1985
Summary
Pig epidermal cells contain polyamine-dependent protein kinase (P kinase) that phosphorylates specific proteins, including ornithine decarboxylase (ODC), reducing its activity. This kinase plays a role in cellular regulation.
Area of Science:
- Biochemistry
- Cell Biology
- Dermatology
Background:
- Protein kinases regulate cellular functions through phosphorylation.
- Polyamines are essential for cell growth and differentiation.
- Understanding epidermal cell kinase activity is crucial for skin biology.
Purpose of the Study:
- To characterize polyamine-dependent protein kinase (P kinase) in pig epidermal cells.
- To identify substrates and regulatory roles of P kinase.
- To investigate the interaction between P kinase and ornithine decarboxylase (ODC).
Main Methods:
- Extraction and purification of protein kinases from nuclear and cytosol fractions.
- Phosphorylation assays using histone and non-histone proteins.
- Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) for polypeptide analysis.
- Kinetic studies to assess enzyme activity.
Main Results:
- Two nuclear protein kinases were purified: cAMP-dependent protein kinase (A kinase) and P kinase.
- P kinase specifically phosphorylated acidic non-histone proteins, including a 180 kDa polypeptide.
- Cytosolic P kinase phosphorylated an 80 kDa polypeptide that comigrated with ornithine decarboxylase (ODC).
- Phosphorylation of ODC by P kinase led to a decrease in its enzymatic activity.
Conclusions:
- Pig epidermal cells possess distinct nuclear and cytosolic P kinases with specific substrate preferences.
- P kinase directly phosphorylates and inhibits ornithine decarboxylase (ODC) activity.
- This finding suggests a regulatory role for P kinase in polyamine metabolism within epidermal cells.