A MICROTUBULE-ASSOCIATED PROTEIN IN MAIZE IS EXPRESSED DURING PHYTOCHROME-INDUCED CELL ELONGATION

Citation
P. Nick et al., A MICROTUBULE-ASSOCIATED PROTEIN IN MAIZE IS EXPRESSED DURING PHYTOCHROME-INDUCED CELL ELONGATION, Plant journal, 8(6), 1995, pp. 835-844
Citations number
41
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Plant Sciences",Biology
Journal title
ISSN journal
0960-7412
Volume
8
Issue
6
Year of publication
1995
Pages
835 - 844
Database
ISI
SICI code
0960-7412(1995)8:6<835:AMPIMI>2.0.ZU;2-#
Abstract
Plants can adapt their shape to environmental stimuli. This response i s mediated by the reorganization of cortical microtubules, a unique el ement of the cytoskeleton. However, the molecular base of this respons e has remained obscure so far. In an attempt to solve this problem, si gnal-dependent changes in the pattern of microtubule-binding proteins were analysed during coleoptile elongation in maize, that is, under th e control of the plant photoreceptor phytochrome. Two putative MAPs of 100 kDa (P-100) and 50 kDa apparent molecular weights were identified in cytosolic extracts from non-elongating and elongating cells. Both proteins co-assembled with endogenous tubulin, bound to neurotubules a nd were immunologically related to the neural MAP tau: the P-100 prote in, depending on the physiological situation, was manifest as a double band and was always found to be heat-stable. In contrast, the 50 kDa MAP was heat-stable only for particular tissues and physiological trea tments. The P-100 protein was present in all tissues, however in a red uced amount in elongating coleoptiles. The 50 kDa MAP was expressed ex clusively upon induction of phytochrome-dependent cell elongation. As shown by immunofluorescence double-staining, an epitope shared by both proteins colocalized with cortical microtubules in situ, but exclusiv ely in elongating cells. In non-elongating cells, only the nuclei were stained. Partially purified nuclei from elongating cells were enriche d in P-100, whereas the 50 kDa MAP became enriched in a partially puri fied plasma membrane fraction.