Phosphatidylinositol 4,5-bisphosphate stimulates protein kinase C-mediated phosphorylation of soluble brain proteins : inhibition by neomycin

• Published in: FEBS letters 1990-10, Vol.272 (1-2), p.99-102
• Main Author: CHAUHAN, V. P. S
• Format: Article
• Language: English
• Subjects: Adenosine Triphosphate - metabolism; Analytical, structural and metabolic biochemistry; Animals; Biological and medical sciences; Calcium - metabolism; Cerebral Cortex - metabolism; Diglycerides - pharmacology; Enzyme Activation - drug effects; Enzymes and enzyme inhibitors; Fundamental and applied biological sciences. Psychology; Molecular Weight; Neomycin - pharmacology; Nerve Tissue Proteins - metabolism; Phosphatidylinositol 4,5-Diphosphate; Phosphatidylinositols - pharmacology; Phosphorylation; Protein Kinase C - antagonists & inhibitors; Protein Kinase C - metabolism; Rats
• ISSN: 0014-5793; 1873-3468

Phosphatidylinositol 4,5-bisphosphate (PIP2) at 0.1 mol% activated the protein kinase C (PKC)-mediated phosphorylation of 87-, 55- and 47-kDa brain proteins. Neomycin, an aminoglycoside antibiotic that binds PIP2 with a high affinity, inhibited PIP2.PKC activity in a concentration-dependent manner. Low concentrations of neomycin (less than 2 mM) did not affect DG.PKC activity; however, 4 mM neomycin inhibited 50% of this activity. This inhibition of DG-stimulated activity at high neomycin concentration may be the result of its binding to Ca2+ and ATP in the assay system. These results suggest that PIP2 is a physiological activator of PKC, and show that neomycin can be an inhibitor of PIP2.PKC activity at concentrations where DG.PKC activity is not affected.