SOMETHING FROM NOTHING - THE EVOLUTION AND UTILITY OF SATELLITE REPEATS

Large blocks of tandemly repeated sequences, or satellites, surround t he centromeres of complex eukaryotes. during mitosis in Drosophila, sa tellite DNA binds proteins that, during interphase, bind other sites. The requirement for a repeat to borrow a partner protein from those av ailable at mitosis with limit the spectrum of repeat units that can be expanded into large blocks. To account for the ubiquity and pericentr ic localization of satellites, we propose that they are utilized to ma intain regions of late replication, thus ensuring that the centromere is the last region to replicate on a chromosome.