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GrainGenes Reference Report: PGR-32-329

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Reference
PGR-32-329
Title
Nuclear and chloroplast cytokinin-binding proteins from barley leaves participating in transcription regulation
Journal
Plant Growth Regulation
Year
2000
Volume
32
Pages
329-335
Author
Kulaeva ON
[ Show all 10 ]
Abstract
Summary: The 67 kDa cytokinin-binding protein (CBP) previously isolated from the cytosol of mature leaves of 10-day-old barley seedlings has now been purified from nuclei isolated from the same leaves. The procedure of CBP isolation included protein purification by Sephadex G-50, hydrophobic chromatography on phenyl-Sepharose and affinity chromatography on zeatin-Sepharose. Interaction of trans-zeatin with the nuclear protein was demonstrated by the ELISA technique based on cytokinin competition with anti-idiotype antibodies (raised against antibodies to trans-zeatin) for complex formation with the protein immobilized on polystyrene microtiter plates. Nuclear 67 kDa protein in concert with trans-zeatin activated transcription elongation in vitro in systems containing chromatin associated with RNA polymerase I or nuclei isolated from barley leaves. Nuclear 67 kDa protein had no effect on the chloroplast transcription system. A 64 kDa CBP was isolated from chloroplasts of barley leaves by the same procedure as that used for CBP isolation from nuclei. The cytokinin-binding properties of the chloroplast protein were demonstrated by competition of trans-zeatin with Ab(a-i) in complex formation with the protein in ELISA. Chloroplast CBP activated RNA synthesis markedly in chloroplast lysate without any effect on transcription in the chromatin-containing system. Therefore both nuclear and chloroplast transcription machineries are regulated by cytokinins by means of special nuclear and chloroplast cytokinin-binding proteins which can be considered cytokinin receptors with the properties of transfactors regulating the elongation phase of transcription
Keyword
[ Hide all but 1 of 40 ]
affinities
affinity chromatography
antibody
barley
barley leaves
barley seedlings
binding proteins
cbp
chloroplast
chloroplast protein
chromatin
chromatography
competition
complex-formation
complexes
cytokinin
cytosol
elisa
elongation
genetic regulation
hordeum vulgare
in vitro
interaction
isolation
nuclei
phase
plant composition
polymerase
properties
protein
purification
receptor
regulation
rna polymerase
seedling
synthesis
system
transcription
transcription elongation
vitro

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