Figure 6.

Model for the requirement of Ska for stable KT–MT interactions. As summarized in this schematic, we propose that the KMN network and the Ska complex cooperate to ensure stable end-on MT attachments to KTs (top panel). Stable attachment fails upon depletion of either the KMN or the Ska complex. In the absence of KMN (middle panel), the Ska complex fails to localize to KTs, whereas, conversely, the KT localization of the KMN does not strictly depend on the Ska complex (bottom panel). This implies that the KMN alone is not sufficient for stable MT attachment but requires cooperation with the Ska complex for full functionality. Finally, we emphasize that the role in chromosome congression shown here for the Ska complex does not rigorously exclude a second, additional role for this complex in SAC silencing (Hanisch et al, 2006).