A protein involved in homologous recombination. A single strand of DNA coated in RecA is capable of invading a double helix providing that some degree of homology is present. One of the original strands will be displaced from the triplex intermediate, leaving a new double stranded section. Mismatch correction may then repair any mismatches between the two strands. RecA is required for recombination to be possible in meiotic recombination, where it allows the strand freed by RecB, C and D to invade the homologous chromosome.