THE ELUSIVE CENTROMERE - SEQUENCE DIVERGENCE AND FUNCTIONAL CONSERVATION

The centromere is an essential cis-acting structure present in the chr omosomes of all eukaryotes, central to the mechanism that ensures prop er segregation during meiosis and mitosis. Molecular characterization of centromeres in the budding and fission yeasts has advanced signific antly over the last few years due to their relatively small size and t he availability of functional assays. However, identification and char acterization of centromeric sequences from multicellular organisms has proven to be slow and difficult in the absence of direct functional t ests. Molecular data have recently become available on the centromere of Drosophila, making it possible Co bridge a long-standing gap in our knowledge on the general structure of centromeres. An evaluation of t he available data from yeast to man suggests that centromere sequence and centromere sequence organization have diverged significantly, even amongst different chromosomes of a single organism; however, overall centromere organization and kinetochore components might be significan tly more conserved than thought previously.