 The RPA protein , which has high affinity for single @-@ stranded DNA , then binds the 3 ' overhangs . With the help of several other proteins that mediate the process , the Rad51 protein ( and Dmc1 , in meiosis ) then forms a filament of nucleic acid and protein on the single strand of DNA coated with RPA . This nucleoprotein filament then begins searching for DNA sequences similar to that of the 3 ' overhang . After finding such a sequence , the single @-@ stranded nucleoprotein filament moves into ( invades ) the similar or identical recipient DNA duplex in a process called strand invasion . In cells that divide through mitosis , the recipient DNA duplex is generally a sister chromatid , which is identical to the damaged DNA molecule and provides a template for repair . In meiosis , however , the recipient DNA tends to be from a similar but not necessarily identical homologous chromosome . A displacement loop ( D @-@ loop ) is formed during strand invasion between the invading 3 ' overhang strand and the homologous chromosome . After strand invasion , a DNA polymerase extends the end of the invading 3 ' strand by synthesizing new DNA . This changes the D @-@ loop to a cross @-@ shaped structure known as a Holliday junction . Following this , more DNA synthesis occurs on the invading strand ( i.e. , one of the original 3 ' overhangs ) , effectively restoring the strand on the homologous chromosome that was displaced during strand invasion . 
