Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.4.3 (phospholipase C)
 18,461 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In comparison with other cell organelles, the Dunaliella salina plasma membrane was found to be highly enriched in phospholipase C activity toward exogenous [(3)H]phosphatidylinositol 4,5-bisphosphate (PIP(2)). Based on release of [(3)H]inositol phosphates, the plasma membrane exhibited a PIP(2)-phospholipase C activity nearly tenfold higher than the nonplasmalemmal, nonchloroplast ;bottom phase' (BP) membrane fraction and 47 times higher than the chloroplast membrane fraction. The majority of phospholipase activity was clearly of a phospholipase C nature since over 80% of [(3)H]inositol phosphates released were recovered as [(3)H]inositol trisphosphate (IP(3)). These results suggest a plausible mechanism for the rapid breakdown of PIP(2) and phosphatidylinositol 4-phosphate (PIP) following hypoosmotic shock. Quantitative analysis of major [(3)H]inositol phospholipids during these assays revealed that some of the [(3)H]-PIP(2) was converted to [(3)H]phosphatidylinositol 4-monophosphate (PIP) and to [(3)H]phosphatidyl-inositol (PI) in the BP fraction of membrane remaining after removal of plasmalemma and chloroplasts. This latter fraction is enriched more than fivefold in PIP(2)/PIP phosphomonoesterase activity when compared to the plasmalemma or chloroplast membrane fractions. We have also examined some of the in vitro characteristics of the plasma membrane phospholipase C activity and have found it to be calcium sensitive, reaching maximal activity at 10 micromolar free [Ca(2+)]. We also report here that 100 micromolar GTPgammaS stimulates phosphospholipase C activity over a range of free [Ca(2+)]. Together, these results provide evidence that the plasma membrane PIP(2)-phospholipase C of D. salina may be subject to Ca(2+) and G-protein regulation.
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PMID:Phosphatidylinositol 4,5-Bisphosphate Phospholipase C and Phosphomonoesterase in Dunaliella salina Membranes. 1666 60

Although it has been well demonstrated that decapitation insult results in a rapid breakdown of the poly-phosphoinositides in brain, the subcellular site(s) for this event has not been examined in detail. Using rats that were injected intracerebrally with (32)Pi to label the brain membrane phosphoinositides, decapitation treatment (0.5, 1.5 and 3.5 min) resulted in a decrease in labeled phosphatidylinositol 4,5-bisphosphates and phosphatidylinositol 4-phosphates in almost all subcellular fractions except myelin. However, the fractions exhibiting the most changes were synaptic vesicles, synaptic plasma membranes and the non-synaptic plasma membranes. The rapid response of poly-phosphoinositides in synaptic vesicles towards decapitation insult demonstrated a role of these phospholipids in vesicular membrane function. Besides the decrease in labeled phosphatidylinositol 4,5-bisphosphates which is attributed mainly to the action of phospholipase C, decapitation insult also elicited a near parallel decrease in labeled phosphatidylinositol 4-phosphates, and this was accompanied by a concomitant increase in labeled phosphatidylinositol which was observed mainly in the synaptic vesicles and synaptic plasma membrane fractions. This latter event suggests that besides degradation of phosphatidylinositol 4,5-bisphosphates by phospholipase C, some phosphatidylinositol 4-phosphates may have been degraded through the phosphomonoesterase pathway.
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PMID:Degradation of poly-phosphoinositides in brain subcellular membranes in response to decapitation insult. 2050 55


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