title: Characterization of a 200 kDa microtubule-associated protein of tobacco BY-2 cells, a member of the XMAP215/MOR1 family.
abstract: 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.
authors.affiliation: Department of Life Science, Graduate School of Life Science, Hyogo University, Harima Science Park City, Hyogo, 678-1297 Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Hamada
authors.forename: Hisako
authors.initials: H
authors.lastname: Igarashi
authors.forename: Tomohiko J
authors.initials: TJ
authors.lastname: Itoh
authors.forename: Teruo
authors.initials: T
authors.lastname: Shimmen
authors.forename: Seiji
authors.initials: S
authors.lastname: Sonobe
mesh_terms: D001704:Biopolymers; D002460:Cell Line; D019281:Dimerization; D008856:Microscopy, Fluorescence; D008869:Microtubule-Associated Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D008970:Molecular Weight; D011485:Protein Binding; D014026:Nicotiana / Q000166:cytology*
chemical_list: D001704:Biopolymers; D008869:Microtubule-Associated Proteins