The protein kinase C, calcium-independent and calcium-dependent kinase activities of glial cells in primary culture and subculture.
The activity of calcium-independent, calcium-dependent and calcium + phospholipid-dependent (protein kinase C) kinases in cytosol fractions from rat brain glial cells in primary culture and from subcultured astrocytes and in oligodendrocyte-type 2 astrocyte lineage glia has been measured with histone Type IIIS as substrate. Accurate measurement of protein kinase C activity was achieved only after chromatography of glial cytosols on DE-52 anion exchange columns to remove an endogenous inhibitor, identified tentatively as a phosphatase possibly of the protein phosphatase 2A class. The specific activity of protein kinase C in glial cell cytosol increased from 7.5 +/- 0.8 to 37.9 +/- 0.9 nmol32P incorporated/mg protein/10 min with increasing culture age. Protein kinase C activity in glial cytosol was significantly higher when primary cultures were grown in a defined medium lacking serum. Astrocyte-conditioned medium and phorbol esters caused a rapid translocation of glial cell protein kinase C activity from cytosol to membrane compartments. Myelin basic protein and protamine have been compared with histone as substrates for measurement of calcium-independent, calcium-dependent and calcium + phospholipid-dependent kinase activities in glial cytosol.
Department of Biology, University of York, England.
J A
JA
Murphy
R
R
Turner
M G
MG
Rumsby
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D003600:Cytosol / Q000378:metabolism; D009457:Neuroglia / Q000378:metabolism*; D010770:Phosphotransferases / Q000378:metabolism*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051381:Rats
D010770:Phosphotransferases; D011493:Protein Kinase C; D002118:Calcium