RAD51 and DMC1 form mixed complexes associated with mouse meiotic chromosome cores and synaptonemal complexes

The eukaryotic RecA homologues RAD51 and DMC1 function in homology recognit ion and formation of joint-molecule recombination intermediates during yeas t meiosis. The precise immunolocalization of these two proteins on the meio tic chromosomes of plants and animals has been complicated by their high de gree of identity at the amino acid level. With antibodies that have been im munodepleted of cross-reactive epitopes, we demonstrate that RAD51 and DMC1 have identical distribution patterns in extracts of mouse spermatocytes in successive prophase I stages, suggesting coordinate functionality. Immunof luorescence and immunoelectron microscopy with these antibodies demonstrate colocalization of the two proteins on the meiotic chromosome cores at earl y prophase I. We also show that mouse RAD51 and DMC1 establish protein-prot ein interactions with each other and with the chromosome core component COR 1(SCP3) in a two-hybrid system and in vitro binding analyses. These results suggest that the formation of a multiprotein recombination complex associa ted with the meiotic chromosome cores is essential for the development and fulfillment of the meiotic recombination process.