Journal Article

Characterization of a 200 kDa Microtubule-associated Protein of Tobacco BY-2 Cells, a Member of the XMAP215/MOR1 Family

Takahiro Hamada, Hisako Igarashi, Tomohiko J. Itoh, Teruo Shimmen and Seiji Sonobe

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 45, issue 9, pages 1233-1242
Published in print September 2004 | ISSN: 0032-0781
Published online September 2004 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pch145
Characterization of a 200 kDa Microtubule-associated Protein of Tobacco BY-2 Cells, a Member of the XMAP215/MOR1 Family

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A microtubule-associated protein composed of a 200 kDa polypeptide (MAP200) was isolated from tobacco-cultured BY-2 cells. Analysis of the partial amino acid sequence showed that MAP200 was identical to TMBP200, the tobacco MOR1/XMAP215 homolog. Although several homolog proteins in animal and yeast cells have been reported to promote MT dynamics in vitro, no such function has been reported for plant homologs. Turbidity measurements of tubulin solution suggested that MAP200 promoted tubulin polymerization, and analysis by dark-field microscopy revealed that this MAP increased both the number and length of microtubules (MTs). Electron microscopy and experiments using a chemical crosslinker demonstrated that MAP200 forms a complex with tubulin. Throughout the cell cycle, some MAP200 colocalized with MT structures, including cortical MTs, the preprophase band, spindle and phragmoplast, while some MAP200 was localized in areas lacking MTs. Based on our biochemical and immunofluorescence findings, the function of MAP200 in MT polymerization is discussed.

Keywords: Keywords: Microtubule — Microtubule-associated protein (MAP) — MOR1 — Tobacco BY-2 cell — XMAP215.; Abbreviations: CBB, Coomassie Brilliant Blue; DTT, dithiothreitol; EGTA, ethyleneglycol bis (2-aminoethylether) tetraacetic acid; PIPES, piperazine-N,N′-bis (2-ethanesulfonic acid); PMSF, phenylmethylsulfonyl fluoride; WSC, 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide, hydrochloride.

Journal Article.  5504 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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