Abstract
Guanyl-5'-yl imidodiphosphate (p[NH]ppG) stimulated a rapid phospholipase C-mediated breakdown of exogenously added phosphatidylinositol 4,5-bisphosphate (PIP2) in rat cerebral-cortical membranes, with half-maximal activation at approx. 33 μM. NaF stimulated phospholipase C activity, with half-maximal activation at 0.5 mM. Stimulation of phospholipase C activity of NaF exhibited pH optima at approx. 5.5 and 7.0, with the stimulatory activity at pH 7.0 greater than that of pH 5.5. With p[NH]ppG, only stimulation at pH 7.0 was observed. Neither p[NH]ppG nor NaF stimulated hydrolysis of added phosphatidylinositol (PI) or phosphatidylinositol 4-phosphate (PIP). Mg2+ (0.5 mM) potentiated p[NH]ppG-stimulated breakdown of PIP2. Ca2+ increased basal and p[NH]ppG-stimulated breakdown of PIP2. PI breakdown was stimulated only by high Ca2+ concentrations and was unaffected by p[NH]ppG at any Ca2+ concentration examined. These results indicate that, in cerebral-cortical membranes, activation of phospholipase C by guanine nucleotides or fluoride directly increases a phospholipase C activity which specifically hydrolyses PIP2.
Original language | English (US) |
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Pages (from-to) | 35-40 |
Number of pages | 6 |
Journal | Biochemical Journal |
Volume | 244 |
Issue number | 1 |
DOIs | |
State | Published - 1987 |
Externally published | Yes |
ASJC Scopus subject areas
- Biochemistry
- Molecular Biology
- Cell Biology