Tetrahymena and Paramecium species are widely used representatives of the phylum Ciliata. Ciliates are particularly suitable model organisms for studying the functional heterogeneity of tubulins, since they provide a wide range of different microtubular structures in a single cell. Sequencing projects of the genomes of members of these two genera are in progress. Nearly all members of the tubulin superfamily (alpha-, beta-, gamma-, delta-, epsilon-, eta-, theta-, iota-, and kappa-tubulins) have been identified in Paramecium tetraurelia. In Tetrahymena spp., the functional consequences of different posttranslational tubulin modifications (acetylation, tyrosination and detyrosination, phosphorylation, glutamylation, and glycylation) have been studied by different approaches. These model organisms provide the opportunity to determine the function of tubulins found in ciliates, as well as in humans, but absent in some other model organisms. They also give us an opportunity to explore the mechanisms underlying microtubule diversity. Here we review current knowledge concerning the diversity of microtubular structures, tubulin genes, and posttranslational modifications in Tetrahymena and Paramecium species.
- MeSH
- Cilia chemistry MeSH
- Financing, Organized MeSH
- Microtubules chemistry MeSH
- Paramecium cytology genetics chemistry MeSH
- Protein Processing, Post-Translational MeSH
- Tetrahymena cytology genetics chemistry MeSH
- Tubulin genetics chemistry MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Review MeSH
Many of the highly organized microtubular arrangements in ciliates are located in the cortical area containing membrane vesicles and vacuoles. In Tetrahymena thermophila and Paramecium caudatum, immunofluorescence microscopy with the monoclonal antibody TU-06, directed against beta-tubulin, revealed distinct staining of this cortical region alone, while the cilia and other microtubular structures were unstained. The specificity of the antibody was confirmed by immunoblotting and by preabsorption of the antibody with purified tubulin. Double-label immunofluorescence with antibodies against gamma-tubulin, detyrosinated alpha-tubulin, and centrin showed that the TU-06 epitope is localized outside the basal body region. This was also confirmed by immunogold electron microscopy of thin sections. Proteolytic digestion of porcine brain beta-tubulin combined with a peptide scan of immobilized, overlapping peptides disclosed that the epitope was in the beta-tubulin region beta81-95, a region which is phylogenetically highly conserved. As known posttranslational modifications of beta-tubulin are located outside this area, the observed staining pattern cannot be interpreted as evidence of subcellular sequestration of modified tubulin. The limited distribution of the epitope could rather reflect the dependence of TU-06 epitope exposition on conformations of tubulin molecules in microtubule arrangements or on differential masking by interacting proteins.
- MeSH
- Cell Membrane immunology MeSH
- 3T3 Cells MeSH
- Epitopes analysis immunology metabolism MeSH
- Financing, Organized MeSH
- Immunoblotting MeSH
- Epitope Mapping MeSH
- Mice MeSH
- Paramecium immunology MeSH
- Tetrahymena thermophila immunology MeSH
- Tubulin immunology MeSH
- Animals MeSH
- Check Tag
- Mice MeSH
- Animals MeSH
- MeSH
- Cell Cycle MeSH
- Research Support as Topic MeSH
- Leishmania tropica cytology chemistry MeSH
- Subcellular Fractions metabolism MeSH
- Tubulin chemistry metabolism MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Comparative Study MeSH
