Planta (2008) 229:143–150 DOI 10.1007/s00425-008-0816-z 123 ORIGINAL ARTICLE Tyrosine phosphorylation of plant tubulin Yaroslav Blume · Alla Yemets · Vadym Sulimenko · Tetyana Sulimenko · Jordi Chan · Clive Lloyd · Pavel Dráber Received: 5 June 2008 / Accepted: 15 August 2008 / Published online: 18 September 2008  Springer-Verlag 2008 Abstract Phosphorylation of -tubulins dimers by protein tyrosine kinases plays an important role in the regulation of cellular growth and diVerentiation in animal cells. In plants, however, the role of tubulin tyrosine phos- phorylation is unknown and data on this tubulin modiWca- tion are limited. In this study, we used an immunochemical approach to demonstrate that tubulin isolated by both immunoprecipitation and DEAE-chromatography is phos- phorylated on tyrosine residues in cultured cells of Nicoti- ana tabacum. This opens up the possibility that tyrosine phosphorylation of tubulin could be involved in modulating the properties of plant microtubules. Keywords Plant microtubules · Post-translational modiWcations · Phosphorylation · Tubulin · Tyrosine residues Introduction Microtubules are necessary for a wide spectrum of cellular functions, including cell division, cell wall deposition, intracellular transport, organelle positioning, cell motility, and establishment of cell polarity. Distinct types of micro- tubular arrays form transiently in higher plant cells as they proceed through the cell cycle: the interphase network of cortical microtubules, the preprophase band, mitotic spin- dle, and phragmoplast. The main components of microtu- bules, - and -tubulins, are known to be polymerized from a multiplicity of isotypes. This originates from expression of a multigene family (Breviario 2000), but isoform hetero- geneity is increased by as variety of post-translational mod- iWcations. In animals, such modiWcations give rise to a large number of - and -tubulin isoforms (Westermann and Weber 2003), generating populations of microtubules with diVerent functions. Although there is evidence that plant tubulin is post- translationally modiWed (Duckett and Lloyd 1994; Blume et al. 1997; Smertenko et al. 1997; Gilmer et al. 1999a, b; Huang and Lloyd 1999; Wang et al. 2004), the functional role of these modiWcations is not known. Some modiWca- tions have not been described for plant tubulin: e.g., nitro- sylation and palmitoylation. In animals, tyrosine phosphorylation has been found on -tubulin (Akiyama et al. 1986; Wandosell et al. 1987; Maness and Matten 1990; Matten et al. 1990; Ley et al. 1994; Ishibashi et al. 1999) and -tubulin (Akiyama et al. 1986; Wandosell et al. 1987; Maness and Matten 1990; Matten et al. 1990), and is known to play a key role in cellular growth and diVerentia- tion. Recent large-scale phosphorylation mapping projects revealed several peptides phosphorylated on serine or thre- onine in Arabidopsis - and -tubulins (Heazlewood et al. 2007; Sugiyama et al. 2008; De la Fuente van Bentem et al. Y. Blume (&) · A. Yemets Institute of Cell Biology and Genetic Engineering, National Academy of Sciences of Ukraine, Acad. Zabolotny Str., 148, 03680 Kiev, Ukraine e-mail: cellbio@cellbio.freenet.viaduk.net; yablume@univ.kiev.ua V. Sulimenko · T. Sulimenko · P. Dráber Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Building LB, Videnska 1083, 142 20 Prague 4, Czech Republic J. Chan · C. Lloyd Department of Cell and Developmental Biology, John Innes Centre, Norwich NR4 7UH, UK