caa a22 4500 477100309 CHVBK 20180405111539.0 cr unu---uuuuu 170330e19961001xx s 000 0 eng 10.1007/BF00208306 doi (NATIONALLICENCE)springer-10.1007/BF00208306 Light regulation of phosphoenolpyruvate carboxylase in barley mesophyll protoplasts is modulated by protein synthesis and calcium, and not necessarily correlated with phosphoenolpyruvate carboxylase kinase activity [Elektronische Daten] [Lucy Smith, Cathrine Lillo, Hugh Nimmo, Malcom Wilkins] The regulation of phosphoenolpyruvate carboxylase (PEPCase, EC. 4.1.1.31) and PEPCase kinase was investigated using barley (Hordeum vulgare L.) mesophyll protoplasts. Incubation of protoplasts in the light resulted in a reduction in the sensitivity of PEPCase to the inhibitor L-malate; PEPCase from protoplasts incubated in the light for 1 h was inhibited 48±2% by 2mM malate, whereas the enzyme from protoplasts incubated for 1 h in the dark was inhibited by 67±2%. Light-induced reduction of sensitivity of PEPCase to malate was decreased by cycloheximide (CHM), indicating the involvement of protein synthesis. The PEPCase kinase in protoplasts increased with time after isolation in darkness, and increased still further following light treatment. The increase in kinase activity in the light was sensitive to CHM. When protoplasts were illuminated in the presence of EGTA and the calcium ionophore A23187 to reduce intracellular Ca2+, the reduction in the senstivity of PEPCase to malate was enhanced, though no more PEPCase kinase activity was detected than in protoplasts illuminated in the absence of EGTA and A23187. Incubation with 3-(3′,4′-dichlorophenyl)-1,1-dimethylurea (DCMU) had no effect on the light-induced reduction of sensitivity of PEPCase to malate inhibition or on light-activation of PEPCase kinase. These results indicate that there is a constitutive PEPCase kinase activity in C3 leaf tissue, that there is another kinase which is light-activated in a CHMsensitive way, that the sensitivity of PEPCase to its inhibitor may not always be correlated with apparent PEPCase kinase actvity, and that PEPCase and PEPCase kinase are regulated in a different manner in C3 protoplasts than in C4 protoplasts or leaf tissue. Springer-Verlag, 1996 Barley nationallicence Hordeum nationallicence Kinase nationallicence Phosphoenol nationallicence pyruvate carboxylase nationallicence Protoplasts nationallicence CAM : Crassulacean acid metabolism nationallicence Chl : chlorophyll nationallicence CHM : cycloheximide nationallicence DCMU : 3-(3′,4′-dichloro-phenyl)-1,1-dimethylurea nationallicence PEP : phosphoenolpyruvate nationallicence PEPCase : PEP carboxylase nationallicence Smith Lucy Division of Biochemistry and Molecular Biology, Institute of Biomedical and Life Sciences, Bower Building, University of Glasgow, G12 8QQ, Glasgow, UK aut Lillo Cathrine Division of Biochemistry and Molecular Biology, Institute of Biomedical and Life Sciences, Bower Building, University of Glasgow, G12 8QQ, Glasgow, UK aut Nimmo Hugh Division of Biochemistry and Molecular Biology, Institute of Biomedical and Life Sciences, Bower Building, University of Glasgow, G12 8QQ, Glasgow, UK aut Wilkins Malcom Division of Biochemistry and Molecular Biology, Institute of Biomedical and Life Sciences, Bower Building, University of Glasgow, G12 8QQ, Glasgow, UK aut Planta Springer-Verlag 200/2(1996-10-01), 174-180 0032-0935 200:2<174 1996 200 425 https://doi.org/10.1007/BF00208306 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00208306 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Smith Lucy Division of Biochemistry and Molecular Biology, Institute of Biomedical and Life Sciences, Bower Building, University of Glasgow, G12 8QQ, Glasgow, UK aut NATIONALLICENCE 700 1- Lillo Cathrine Division of Biochemistry and Molecular Biology, Institute of Biomedical and Life Sciences, Bower Building, University of Glasgow, G12 8QQ, Glasgow, UK aut NATIONALLICENCE 700 1- Nimmo Hugh Division of Biochemistry and Molecular Biology, Institute of Biomedical and Life Sciences, Bower Building, University of Glasgow, G12 8QQ, Glasgow, UK aut NATIONALLICENCE 700 1- Wilkins Malcom Division of Biochemistry and Molecular Biology, Institute of Biomedical and Life Sciences, Bower Building, University of Glasgow, G12 8QQ, Glasgow, UK aut NATIONALLICENCE 773 0- Planta Springer-Verlag 200/2(1996-10-01), 174-180 0032-0935 200:2<174 1996 200 425 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer