The early Caenorhabditis elegans embryo contains abundant transcripts for two α-and two β-tubulins raising the question of whether each isoform performs specialized functions or simply contributes to total tubulin levels. Our identification of two recessive, complementing alleles of a β-tubulin that disrupt nuclear-centrosome centration and rotation in the early embryo originally suggested that...

Microtubules are hollow tube-like polymeric structures composed of α,β-tubulin heterodimers. They play an important role in numerous cellular processes, including intracellular transport, cell motility and segregation of the chromosomes during cell division. Moreover, microtubule doublets or triplets form a scaffold of a cilium, centriole and basal body, respectively. To perform such diverse fu...

*Department of Biochemistry noff et al., 1989; Ostermann et al., 1989; Martin et al., New York University Medical Center 1991; Gething and Sambrook, 1992; Gao et al., 1992; New York, NY 10016 Horwich et al., 1993; Lewis et al., 1996). †Flanders Interuniversity Institute for Biotechnology It has not provedpossible to obtain exchange-compeUniversity of Ghent tent tubulin following denaturation of...

Differential susceptibility to microtubule agents has been demonstrated between mammalian cells and kinetoplastid organisms such as Leishmania spp. and Trypanosoma spp. The aims of this study were to identify and characterize the architecture of the putative colchicine binding site of Leishmania spp. and investigate the molecular basis of colchicine resistance. We cloned and sequenced the β-tub...

The kaleidoscopic structures in the electron micrographs above are the bundles of microtubules (axonemes) found in moth and fly sperm tail flagella, shown in cross-section. The axonemes above show the pattern typical of cilia and flagella in insects and other arthropods: nine doublet microtubules surround a central pair of singlet microtubules, and each doublet is associated with a singlet 'acc...

The properties of the microtubule network are regulated at various levels including tissue-dependent isotype switching, post-translational modification of αand β-tubulin, and by a variety of microtubuleassociated molecules (for reviews, see [1–3]). Microtubule nucleation is attributed to γ-tubulin, which is present in protein complexes at the centrosome and in the cytoplasm [4,5]. A screen for ...

Microtubules (MTs) are key components of the cytoskeleton for all eukaryotes and are vital for cellular processes such as mitotic spindle formation, intracellular transport, vesicle formation, cellular signaling, and migration. These functions depend on the dynamic nature of MTs, which arises from the polymerization and depolymerization events of individual heterodimers, made up of αand β-tubul...

Microtubule dynamic instability arises from the hydrolysis of GTP bound to the β-monomer of the tubulin dimer. The conformational change induced by hydrolysis is unknown, but microtubules disassemble into protofilaments of GDP-bound tubulin that curve away from the microtubule axis. This paper presents the unfolding of a portion of the tubulin molecule into the microtubule interior as a plausib...