Figure 2.

Speculative models of various Ska functions mediated by “One-pool” or “two-pools” of Ska. In “Two-pools” model, the Ndc80-loop pool of Ska is recruited by the Ndc80 loop, or together with some of its flanking sequences, and the recruitment is also dependent on Cdk1-mediated Ska3 phosphorylation. This pool seems to play a more important role in silencing the spindle checkpoint than stabilizing kinetochore-microtubule interactions. In contrast, the Ndc80-N-terminus pool of Ska is recruited by the N-terminal domains of Ndc80 and appears to be more important for stabilizing kinetochore-microtubule interactions. In “One-pool” model, the Ndc80 loop and N-terminus collaborate to recruit and maintain one major Ska pool at kinetochores. This pool might be responsible for both stabilizing kinetochore-microtubule interactions and silencing the spindle checkpoint.