FIG. 7.

Model of CENP-50 function in the centromere. When cells progress through the cell cycle without problems, CENP-50 is dispensable for chromosome segregation. However, when problems such as spindle abnormalities or kinetochore defects occur during mitosis, cell cycle progression is arrested due to activation of a mitotic checkpoint pathway. At this point, CENP-50 promotes sister chromatid adhesion and prevents premature sister chromatid separation. We propose that CENP-50 functions as a backup mechanism to prevent chromosome abnormalities during delay due to activation of mitotic checkpoints. If this backup system is disrupted, the cells remain in mitosis for a prolonged period and eventually die.