Following double strand break (DSB) formation and strand resection, RAD51 and DMC1 coat single-stranded 3' ends of DNA and catalyze the search for homology and strand invasion into the DNA duplex of the chromosomal homolog (Baumann et al. 1996, Barlow et al. 1997, Benson et al. 1998, Baumann and West 1999, Masson et al. 1999, Sehorn et al. 2004, Murayama et al. 2008). The invading strand displaces the original strand of the chromosomal homolog creating a D-loop structure. Other proteins present in the complex are inferred from cytology (Barlow et al. 1997, Oliver-Bonet et al. 2005, Oliver-Bonet et al. 2007).