Phosphatidylinositol 4,5-bisphosphate phospholipase C activity in particulate preparations from rat brain |
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Authors: | Mieke Bergers Sonja Lendi Paul D. Mier |
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Affiliation: | (1) Department of Dermatology, University Hospital, Ph. van Leydenlaan 25, 6525 EX Nijmegen, The Netherlands |
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Abstract: | We describe the hydrolysis of phosphatidylinositol 4,5-bisphosphate by a particulate rat brain preparation in the presence of the cationic detergent, cetrimide. The optimum cetrimide concentration was in the range 0.2–0.4 mg/ml; at higher or lower concentrations, the reaction rate diminished abruptly, suggesting that the electrical charge density of the micelle is critical for enzymatic attack. In other respects, such as its partial requirement for Ca++ and its pH optimum of about 7.0, the particulate enzyme seems similar to soluble preparations which have been reported previously. Interestingly, the particulate preparation could be stimulated about fourfold by a soluble brain extract in the presence of 1 mM guanosine triphosphate, confirming that the enzyme is the catalytic subunit in a membrane-bound signal-transduction system. |
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