Identification of Phospholipase C Activated by GTPγS in Plasma Membrane of Oat Cell = Identification of Phospholipase C Activated by GTPγS in Plasma Membrane of Oat Cell

다국어 초록 (Multilingual Abstract)

In order to investigate whether phospholipase C (PLC) activity in oat cells is regulated by Gprotein, we have characterized PLC in plasma membranes of oat tissues. To identify the purified plasma membrane, K^+-stimulated, Mg^(2+)-dependent ATPase activity was measured. The activity of ATPase was shown to be proportional to the concentration of membrane protein. To examine the PLC activity regulated by G-protein, we used the inside-out and outside-out plasma membrane mixture isolated from the oat cells. The plasma membrane mixture showed higher PLC activity than the one of the outside-out plasma mem brane. This suggests that PLC activity is located at the cytoplasmic surface of plasma membrane. PLC activity in plasma membrane mixture was dependent on Ca^(2+) with maximum activity at 100 μM Ca^(2+) and it was inhibited by 1 mM EGTA. Using Sep-pak Accell^(TM) Plus QMA chromatography, we found that inositol 1,4,5-trisphosphate (IP₃) was produced in the presence of 10 μM Ca^(2+). The PLC activity in the membrane was enhanced by an activator of G-protein (GTPγS) and not by an inhibitor (GDPβS). This indicates that a G-protein is involved in the activation of PLC in the plasma membrane of oat cells.