Figure 2.

Models of how condensin and Pcs1/Mde4 might function to prevent merotelic attachments.

(A) Pcs1/Mde4 prevents merotelic attachments by loading condensin on kinetochores and by clamping microtubule attachment sites. Both Pcs1/Mde4 and condensin function as a microtubule site clamp. (B) Pcs1/Mde4 prevents merotelic attachments solely by loading of condensin on kinetochores. Condensin clamps together microtubule attachment sites in order to prevent merotelic kinetochore orientation. (C) In the absence of Pcs1 (or Mde4), the kinetochore pool of condensin is strongly reduced, leading to high frequencies of merotelic attachments.