TY  - GEN
T1  - Distribution of γ-tubulin ring complex at the Schizosaccharomyces pombe spindle pole
AU  - Saha, Sajjita
AU  - Unruh, Jay R
AU  - Jaspersen, Sue L
DO  - 10.17912/micropub.biology.000464
UR  - http://beta.micropublication.org/journals/biology/micropub-biology-000464/
AB  - Faithful chromosome segregation during mitosis requires the formation of the mitotic spindle. A key component of the spindle apparatus is microtubules, α- and β-tubulin dimers arranged into thirteen protofilaments. Nucleation of microtubules is catalyzed by microtubule organizing centers (MTOCs) (Moritz et al. 1995; Zheng et al. 1995). MTOCs are structurally diverse, but all are defined by enrichment of the γ-tubulin ring complex (γ-TuRC) composed of repeating tetrameric units of γ-tubulin and γ-tubulin complex proteins (GCPs) arranged in a helical fashion which mimics the microtubule geometry and serves as a template for microtubule nucleation (Figure 1A). Most organisms have five related GCPs (GCP2-6), but budding yeast lacks homologs of GCP4-6 and instead nucleates microtubules with a minimal version of the complex known as the γ-tubulin small complex (γ-TuSC) (reviewed in (Kollman et al. 2011; Lin et al. 2015; Liu et al. 2021; Teixido-Travesa et al. 2012)). Although the fission yeast Schizosaccharomyces pombe contains genes encoding all five GCPs (GCP2/alp4+, GCP3/alp6+, GCP4/gfh1+, GCP5/mod21+ and GCP6/alp16+) in addition to γ-tubulin (GCP1/gtb1+), only the genes encoding subunits corresponding to the γ-TuSC are essential for mitotic growth (Anders et al. 2006; Fujita et al. 2002; Horio et al. 1991; Vardy and Toda 2000; Venkatram et al. 2004). If the γ-TuSC proteins are sufficient for microtubule nucleation, what is the function of the γ-TuRC? Structural analysis of γ-TuRC suggests that it is a better match for microtubule geometry; biochemical studies confirmed the γ-TuRC has an enhanced nucleation activity compared to the γ-TuSC (Erlemann et al. 2012; Oegema et al. 1999; Stearns et al. 1991; Vardy and Toda 2000). In addition, there is also evidence for differential localization of γ-TuSC and γ-TuRC complexes (Gao et al. 2019). The combined effect could translate into molecularly distinct MTOCs with differential microtubule nucleation potential, leading to unique microtubule arrays in different regions of a cell.
PY  - 2021
JO  - microPublication Biology
ER  -