A novel tubulin from Mimosa pudica. Purification and characterization.
From Mimosa pudica fresh leaves and pulvinar callus cells, we have purified tubulin protein using an anion-exchange resin, DEAE-Sephadex A-50, followed by ammonium sulfate fractionation and Sephadex G-200 gel filtration. The purified protein consisted of alpha and beta subunits and trace quantities of other proteins. When analysed by sodium dodecyl sulfate/polyacrylamide gel electrophoresis at pH 8.8, both alpha and beta subunits of tubulin almost comigrated with their counterparts from goat brain. Two-dimensional electrophoresis revealed that this tubulin contains one major alpha-tubulin having a pI value of 7.1 and three beta species having pI values of 6.70, 6.46 and 6.40. Morphologically normal microtubules were observed by electron microscopy; self-polymerization in vitro, even in the cold, can also be achieved. Radioimmunoassays, and also immunoblotting with the antibodies raised against alpha- and beta-tubulins of this plant, showed that the nature of alpha-tubulin is different from that obtained from other sources. This is an example of plant tubulin where strong colchicine binding at 1 microM was observed. This protein constitutes 5-6% of the total extractable protein in the leaves. We propose that movement of the leaves of this plant may be regulated by the presence of a high amount of this protein.
Pal
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Department of Biochemistry, Bose Institute, Calcutta, India.
Roychaudhury
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Pal
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Biswas
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D015153:Blotting, Western; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D004591:Electrophoresis, Polyacrylamide Gel; D046911:Macromolecular Substances; D008854:Microscopy, Electron; D008970:Molecular Weight; D010449:Peptide Mapping; D010944:Plants / Q000378:metabolism*; D014404:Tubulin / Q000302:isolation & purification* / Q000378:metabolism / Q000648:ultrastructure
D046911:Macromolecular Substances; D014404:Tubulin