Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.13.12.5 (aequorin)
 1,451 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Intracellular calcium is a second messenger involved in several processes in yeast, such as mating, nutrient sensing, stress response and cell cycle events. It was reported that glucose addition stimulates a rapid increase in free calcium level in yeast. To investigate the calcium level variations induced by different stimuli we used a reporter system based on the photoprotein aequorin. Glucose addition (50 mM) to nutrient-starved cells induced an increase in free intracellular calcium concentration, mainly due to an influx from external medium. The increase of calcium reached its maximum 100-120 s after the stimulus. A concentration of about 20 mM glucose was required for a 50% increase in intracellular calcium. This response was completely abolished in strain plc1 Delta and in the isogenic wild-type strain treated with 3-nitrocoumarin, a phosphatidylinositol-specific phospholipase C inhibitor, suggesting that Plc1p is essential for glucose-induced calcium increase. This suggests that Plc1p should have a significant role in transducing glucose signal. The calcium influx induced by addition of high glucose on cells previously stimulated with low glucose levels was inhibited in strains with a deletion in the GPR1 or GPA2 genes, which suggests that glucose would be detected through the Gpr1p/Gpa2p receptor/G protein-coupled (GPCR) complex. Moreover, the signal was completely abolished in a strain unable to phosphorylate glucose, which is consistent with the reported requirement of glucose phosphorylation for GPCR complex activation.
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PMID:Phospholipase C is required for glucose-induced calcium influx in budding yeast. 1204 85

We investigated the effects of bovine GH (bGH) on Ca(2+) handling, phospholipase C (PLC) activation and inositol 1,4,5-trisphosphate [Ins(1,4,5)P(3)] formation in hepatocytes. bGH generates oscillations in cytosolic free Ca(2+) concentration ([Ca(2+)](i)) in single male rat hepatocytes microinjected with the photoprotein aequorin. In the absence of extracellular Ca(2+) these transients persisted for more than 10 min indicating a requirement for intracellular Ca(2+). Treatment of the hepatocyte with the phosphatidylinositol-specific phospholipase C (PI-PLC) inhibitor U-73122 removed the oscillations. These results suggest bGH-induced oscillations are due to PLC activation and generation of Ins(1,4,5)P(3). We measured the mass of Ins(1,4,5)P(3) in freshly isolated hepatocyte suspensions in response to bGH, and vasopressin as a control. Both agonists rapidly increased the levels of Ins(1,4,5)P(3). This is the first study to indicate that early events in the signal transduction pathways mediated by GH in hepatocytes involve intracellular Ca(2+) mobilization via activation of a PI-PLC and subsequent Ins(1,4,5)P(3) production.
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PMID:The phospholipase C-InsP3 pathway is involved in calcium mobilization induced by growth hormone in hepatocytes. 1512 67