Centromere format

ri io gh din Review TRENDS in Cell Biology Vol.16 No.2 February 2006assembly. The centromere was first described cytologicallychromatid. Kinetochores form the primary interface between chromosomes and the mitotic spindle and mediate microtubule-dependent chromosome movements during mitosis. Kinetochores also sense errors in chromo-some attachment to the mitotic spindle and respond by activating the spindle assembly checkpoint (SAC), which delays the metaphase-to-anaphase transition until all chromosomes achieve bipolar spindle attachment (reviewed in Refs [1–3]). Here, we focus on the centromere, the specialized region of the chromosome that directs kinetochore (Figure 1). The best-characterized complex centromeres are those of the fission yeast Schizosaccharomyces pombe, for which the complete nucleotide sequence of the centromeric DNA of all three chromosomes is known [5]. Each centromere in S. pombe contains a non-repetitive central sequence (cnt) w4–7 kb in length that is flanked by centromere-specific innermost repeats (imr), which together form the site of kinetochore assembly. This central domain is surrounded by long tandem arrays of outer repeats (otr) that are common to all three centromeres in the organism, resulting in total centro-mere lengths of w40–100 kb [6]. Plasmids that contain theattachment, called the kinetochore, on each sister segregation is the assembly of a single site for microtubule centromeres that consist of long stretches of repetitive DNA that are highly divergent between different speciesChromosome Segregation and Aneuploidy s