text: Orc2 (a protein that belongs to the origin recognition complex -ORC- implicated in DNA replication initiation during S phase) is also localized at kinetochores during mitosis in human cells; in agreement with this localization, some studies indicate that Orc2 in yeast is implicated in sister chromatids cohesion, and when it is eliminated from  the cell, spindle checkpoint activation ensues. Some other ORC components (such orc5 in S. pombe) have been also found to participate in cohesion. However, ORC proteins seem to participate in a molecular pathway which is additive to cohesin pathway, and it is mostly unknown.
  Force generation to propel chromosome movement
  Most chromosome movements in relation to spindle poles are associated to lengthening and shortening of kMTs. One of the features of kinetochores is their capacity to modify the state of their associated kMTs (around 20) from a depolymerization state at their (+) end to polymerization state. This allows the kinetochores from cells at prometaphase to show "directional instability", changing between persistent phases of movement towards the pole (poleward) or inversed (anti-poleward), which are coupled with alternating states of kMTs depolymerization and polymerization, respectively. This kinetochore bi-stability seem to be part of a mechanism to align the chromosomes at the equator of the spindle without losing the mechanic connection between kinetochores and spindle poles. It is thought that kinetochore bi-stability is based upon the dynamic instability of the kMTs (+) end, and it is partially controlled by the tension present at the kinetochore. In mammalian cultured cells, a low tension at kinetochores promotes change towards kMTs depolymerization, and high tension promotes change towards kMTs polymerization.