Abstract :
Immunolocalization studies of yeast chromosomes revealed that nuclear proteins topoisomerase II (topoII) is positioned along the axial core of the yeast chromosomes and repressor activator protein 1 (RAP1) is located at the ends of meiotic bivalents. The two nuclear proteins are abundant, multifunctional and bind to specific DNA sequences. Interphase studies showed that RAP1 is found in aggregates near the nuclear membrane while topoII is uniformly dispersed in the yeast nucleus.