Jupiter, a new Drosophila protein associated with microtubules.

ABSTRACT

In this study we describe a novel Drosophila protein Jupiter, which shares properties with several structural microtubule-associated proteins (MAPs) including TAU, MAP2, MAP4. Jupiter is a soluble unfolded molecule with the high net positive charge, rich in Glycine. It possesses two degenerated repeats around the sequence PPGG, separated by a Serine-rich region. Jupiter associates with microtubules in vitro and, fused with the green fluorescent protein (GFP), is an excellent marker to follow microtubule dynamics in vivo. In a jupiter transgenic Drosophila strain generated by the "protein-trap" technique, JupiterGFP fusion protein localizes to the microtubule network through the cell cycle at the different stages of development. We found particularly high JupiterGFP concentrations in the young embryo, larval nervous system, precursors of eye photoreceptors and adult ovary. Moreover, from jupitergfp embryos we have established two permanent cell lines presenting strongly fluorescent microtubules during the whole cell cycle. In these cells, the distribution of the JupiterGFP fusion protein reproduces microtubule behavior upon treatment by the drugs colchicine and taxol. The jupiter cell lines and fly strain should be of wide interest for biologists interested in in vivo analysis of microtubule dynamics.