GLUTAMYLATED TUBULIN PROBED IN CILIATES WITH THE MONOCLONAL ANTIBODY-GT335

Microtubular networks are extensively developped in many ciliate speci es. In several of them, we investigate the occurrence of the post-tran slational glutamylation of tubulin [Edde et al., 1990: Science 247:82- 85; Edde et al., 1991: J. Cell. Biochem. 46:134-142] using as a probe for such modified tubulin, the monoclonal antibody GT335 [Wolff et al. , 1992: Eur. J. Cell Biol. 59:425-432]. Results obtained in Paramecium strongly suggest that both axonemal and cytoplasmic tubulin are gluta mylated. As in the vertebrate brain tubulin so far tested, the GT335 e pitope is located at the carboxy-terminal fragment of cytoplasmic tubu lin removed by subtilisin treatment. Immunoblotting and immunofluoresc ence experiments reveal that, unlike tubulin acetylation, glutamylatio n is not restricted to cold-resistant microtubules. In addition, immun ofluorescence studies performed on dividing cells show that glutamylat ion takes place soon after the polymerization of microtubules. Finally , glutamylated tubulin is also detected in the ciliate species Euplote s, Tetrahymena, and Paraurostyla. Together with results obtained on fl agellate species, this suggests that tubulin glutamylation came out ea rly in the course of eukaryotic evolution and has been widely exploite d in various cellular strategies. (C) 1994 Wiley-Liss, Inc.