A gamma-tubulin antibody against a plant peptide sequence localises to cell division-specific microtubule arrays and organelles in plants

Gamma tubulin (gamma -tubulin) is involved in microtubule initiation in the eukaryotes. In animal cells it is localised to centrosomes and to other, n on-centrosomal sites of microtubule initiation. In addition, cytoplasmic co mplexes containing gamma -tubulin (gamma -TuRCs; gamma -somes) have been de scribed, which are multiprotein complexes involved in microtubule initiatio n. Most localisations of gamma -tubulin in plants have previously been achi eved using an antibody directed towards a conserved peptide sequence found in animal cells, showing co-localisation with all microtubule arrays throug hout the cell cycle. Because different antibodies may give various patterns of subcellular localisation, in the present study we raised a polyclonal a ntibody ('Hayley') to the plant peptide sequence EDFATQGGDRKDVFFY (bold let ters indicate plant-specific amino acids) to further investigate the subcel lular distribution in plants. Immunoblotting using wheat root tip protein e xtracts revealed a 58 kDa gamma -tubulin-like peptide as has been described before. Immunofluorescence microscopy of wheat root-tip cells, however, re vealed localisation of gamma -tubulin to a subset of mitotic microtubule ar rays and the cytokinetic phragmoplast, but not to interphase cortical array s or the preprophase band of microtubules. This lack of labelling may be ca used by a restriction of antibody access during interphase, but more likely by a cell division-specific conformational change in the gamma -tubulin mo lecule. Our antibody also gave an organelle-like labelling, not described b efore, which may represent storage forms or precursors of gamma -tubulin, p erhaps related to plastid-based microtubule initiation in hepatics and horn worts. (C) 2001 Elsevier Science Ltd. All rights reserved.