Figure 6.—
Model for function of Subito in spindle assembly. (A) Schematic of Subito and summary of the functions attributed to each domain. (B) Prior to NEB, Subito does not interact with the microtubules. After NEB, Subito associates with microtubules early in prometaphase. Initially, the majority of microtubules may only interact laterally with the chromosomes (Skold et al. 2005). There may also be kinetochore microtubules forming concurrently (Jang et al. 2005) but the relative timing is not known. In a model for acentrosomal spindle assembly that involves the capture and bundling of microtubules, stabilized plus and minus ends would be expected throughout the spindle, not just near the chromosomes (Jang et al. 2005). Indeed, there is experimental evidence for both microtubule plus and minus ends localized throughout meiotic spindles (Elliott et al. 2005; Burbank et al. 2006). (C) A model for the structure of the spindles when GFP-SubitoΔNT was expressed.