Essential for the onset of septum formation. Involved in the organization of astral microtubules during mitosis. Acts as a bridge between sid4 and the other SIN proteins mediating their association with the spindle pole body (SPB). The sid4-cdc11 complex organizes a signaling hub on the SPB which coordinates cell and nuclear division. Interacts with sid4. When hyperphosphorylated, interacts with byr4. Also interacts with spg1, sid2, cdc13 and cdc16. Localizes at the spindle pole body and the barrier septum. Phosphorylated by cdc7 and cdk1. Hyperphosphorylated during anaphase. Dephosphorylated by par1.