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Identification of Phospholipase C Activated by GTPγS in Plasma Membrane of Oat Cell
Hyae Kyeong Kim,Moon Hwan Park,Quae Chae 생화학분자생물학회 1995 BMB Reports Vol.28 No.5
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.
Kim, Hyae-Kyeong,Kong, Mi-Young,Jeong, Moon-Jin,Han, Dong-Cho,Choi, Jung-Do,Kim, Hak-Yong,Yoon, Kab-Seok,Kim, Jung-Min,Son, Kwang-Hee,Kwon, Byoung-Mog Elsevier 2005 The international journal of biochemistry & cell b Vol.37 No.9
<P><B>Abstract</B></P><P>Actinomycin D was previously reported as an inhibitor of Shc/Grb2 interaction in B104-1-1 cells. Actinomycin D arrested the cell cycle at the G1 phase at 1nM, which is about 10 times lower than the inhibition of Shc/Grb2 interactions in B104-1-1 cells. To evaluate other mechanisms of actinomycin D affected suppression of tumors and cell growth, except inhibition of Shc/Grb2 interactions, we examined the proteomic expression profile by proteomic technology. We found up-regulation of MEKK3 and down-regulation of Hsp70 expression from proteomic analysis, which is a very interesting observation because MEKK3 is strongly related with G1 arrest of cell cycle and Hsp70 is also involved in cell cycle regulation. These results indicate that the anti-tumor effects of actinomycin D is due to synergic effects of various proteins regulated by the compound including inhibition of the Shc/Grb2 interaction and other signaling pathways in the cytoplasm. Here we provide a mechanism-based explanation for growth inhibition by actinomycin D using proteomic technology. Thus, this approach may be a potentially useful method to reveal new mechanisms of active compounds or drugs with unknown cellular function.</P>
Identification of Phospholipase C Activated by $GTP{\gamma}S$ in Plasma Membrane of Oat Cell
Kim, Hyae-Kyeong,Park, Moon-Hwan,Chae, Quae Korean Society for Biochemistry and Molecular Biol 1995 Journal of biochemistry and molecular biology Vol.28 No.5
In order to investigate whether phospholipase C (PLC) activity in oat celIs 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 membrane. 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 ${\mu}m$ $Ca^{2+}$ and it was inhibited by 1 mM EGTA. Using Sep-pak $Accell^{TM}$ Plus QMA chromatography, we found that inositol 1,4,5-trisphosphate ($IP_3$) was produced in the presence of 10 ${\mu}m$ $Ca^{2+}$. The PLC activity in the membrane was enhanced by an activator of G-protein ($GTP{\gamma}S$) and not by an inhibitor ($GDP{\beta}S$). This indicates that a G-protein is involved in the activation of PLC in the plasma membrane of oat cells.