ASSOCIATION OF BRCA1 WITH RAD51 IN MITOTIC AND MEIOTIC CELLS

BRCA1 immunostaining reveals discrete, nuclear foci during S phase of the cell cycle. Human Rad51, a homolog of bacterial RecA, behaves simi larly. The two proteins were found to colocalize in vivo and to coimmu noprecipitate. BRCA1 residues 758-1064 alone formed Rad51-containing c omplexes in vitro. Rad51 is also specifically associated with developi ng synaptonemal complexes in meiotic cells, and BRCA1 and Rad51 were b oth detected on asynapsed (axial) elements of human synaptonemal compl exes. These findings suggest a functional interaction between BRCA1 an d RadB1 in the meiotic and mitotic cell cycles, which, in turn, sugges ts a role for BRCA1 in the control of recombination and of genome inte grity.