Microtubule organizing centers in plant cells: localization of a 49 kDa protein that is immunologically cross-reactive to a 51 kDa protein from sea urchin centrosomes in synchronized tobacco BY-2 cells |
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Authors: | S Hasezawa T Nagata |
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Institution: | (1) Department of Biology, Faculty of Science, University of Tokyo, Bunkyo-ku, 113 Tokyo, Japan |
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Abstract: | Summary A 49 kDa protein in tobacco BY-2 cells has been found to be cross-reactive with antibodies raised against a 51 kDa protein that was isolated from sea urchin centrosomes and identified as a microtubule-organizing center (MTOC) in animal cells. Tracing the fate of the 49 kDa protein during progression of the cell cycle in highly synchronized tobacco BY-2 cells revealed that this protein was colocalized with plant microtubules (MTs): the location of the 49 kDa protein coincided with preprophase bands (PPBs), mitotic spindles and phragmoplasts. Furthermore, between the M and G1 phases, the 49 kDa protein was observed in the perinuclear regions, in which the initials of MTs are organizing to form cortical MTs. At the G1 phase the location of the 49 kDa protein in the cell cortex coincided with that of the cortical MTs. It appeared that the 49 kDa protein in the cell cortex was transported as granules from the perinuclear regions. Thus, it is highly probable that the 49 kDa protein, which reacts with antibodies against the 51 kDa protein in sea urchin centrosomes, plays the role of an MTOC in plant cells. Thus, the mechanisms for organizing MTs in higher organisms appear to share a common protein, even though the organization of MTs is superficially very different in plant and animal cells.Abbreviations DAPI
4,6-diamidino-2-phenyl indole
- MT
microtubule
- MTOC
microtubule-organizing center
- PAGE
polyacrylamide gel electrophoresis
- PBS
phosphate-buffered saline
- PPB
preprophase band
- SDS
sodium dodecylsulfate |
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Keywords: | Cell cycle Microtubule Microtubule organizing center Synchronization Tobacco BY-2 cells |
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