MULTIPLE FORMS OF PROTEIN-KINASE FROM NORMAL HUMAN-BRAIN AND GLIOBLASTOMA

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  • 1 January 1983
    • journal article
    • research article
    • Vol. 43  (3) , 1321-1324
Abstract
The biochemical characteristics of the protein kinase (PK; ATP-protein phosphotransferase, EC 2.7.1.37) isoenzymes in subcellular preparations from normal human brain cortex and glioblastoma were investigated after chromatography on diethylaminoethyl cellulose. Two major isozyme forms, eluted by 50 and 200 mM phosphate buffer, are present in both cytosol and membrane-derived preparations from cerebral cortex. These isozyme forms have properties similar to those referred to as type I and type II cAMP-dependent PK. In these chromatographic isozymes, cAMP is more active in stimulating the basal PK enzyme than is cGMP. In glioblastoma, the PK activity from cytosol and particulate preparations is resolved by diethylaminoethyl cellulose in 4 peaks. In cytosol, the major portion of the enzyme is eluted with a 300 mM buffer (about 50% of the total basal PK activity) and is cyclic nucleotide dependent. In glioblastoma particulate, the PK enzyme is mainly eluted at 50 and 100 mM buffer; neither of these isozymes is cyclic nucleotide dependent. As for cytosol, only the particulate isozyme eluted at 300 mM buffer is strongly activated by cyclic nucleotides. In both glioblastoma subcellular preparations, only a type II cAMP-dependent PK is present.