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Full-Text Articles in Other Biochemistry, Biophysics, and Structural Biology
Lack Of Types 1 And 2a Protein Serine(P)/Threonine(P) Phosphatase Activities In Chloroplasts, Gongqin Sun, John Markwell
Lack Of Types 1 And 2a Protein Serine(P)/Threonine(P) Phosphatase Activities In Chloroplasts, Gongqin Sun, John Markwell
Department of Biochemistry: Faculty Publications
Protein phosphatase activity in crude leaf extracts and in purified intact chloroplasts of wheat (Triticum aestivum) and pea (Pisum sativum) was analyzed using exogenously supplied phosphoproteins or endogenous thylakoid proteins. Leaf extracts contain readily detectable amounts of protein phosphatase activity measured with either phosphohistone or phosphorylase a, substrates of mammalian protein phosphatases. No significant chloroplast protein phosphatase activity was detected using these exogenous phosphoproteins. The dephosphorylation of endogenous thylakoid lightharvesting chlorophyll a/b binding proteins in situ was inhibited by fluoride, but not by microcystin-LR or okadaic acid, diagnostic inhibitors of mammalian types 1 and 2A protein …
Light Activation Of Maize Phosphoenolpyruvate Carboxylase Protein-Serine Kinase Activity Is Inhibited By Mesophyll And Bundle Sheath-Directed Photosynthesis Inhibitors, Jin-An Jiao, Raymond Chollet
Light Activation Of Maize Phosphoenolpyruvate Carboxylase Protein-Serine Kinase Activity Is Inhibited By Mesophyll And Bundle Sheath-Directed Photosynthesis Inhibitors, Jin-An Jiao, Raymond Chollet
Department of Biochemistry: Faculty Publications
C4 phosphoenolpyruvate carboxylase (PEPC) is post-translationally regulated by reversible phosphorylation of a specific N-terminal seryl residue in response to light/dark transitions of the parent leaf tissue. The protein-serine kinase (PEPC-PK) that phosphorylates/activates this mesophyll-cytoplasm target enzyme is slowly, but strikingly, activated by high light and inactivated in darkness in vivo by a mechanism involving cytoplasmic protein synthesis/degradation as a primary component. In this report, evidence is presented indicating that the inhibition of Calvin cycle activity by a variety of mesophyll (3-(3,4-dichlorophenyl)-1,1-dimethylurea, isocil, methyl viologen) and bundle sheath (DL-glyceraldehyde)-directed photosynthesis inhibitors blocks the light activation of maize (Zea mays …