RAD51 is a gene that controls a cell's ability to repair damage to DNA. It does this by binding to single-stranded DNA and helping it form a double helix, which is the necessary first step in the process of replication. RAD51 is part of an important family of genes called recombinases, which allow for precise copying and pasting of genetic material.
The best-known recombinase is probably encoded by the chicken (or avian) papillomavirus (CPV). This virus inserts its genome into that of its host cell and needs RAD51's ability to copy itself before infecting new cells. It is often shared with TRAD, which has the potential to aid with DNA binding. It has been found in all known living organisms, from bacteria to humans.
The RAD51 gene's protein product is a key component of DNA repair, which is how our cells maintain their stability and prevent mutations from accumulating. In the event that the cell does sustain damage to its DNA, such as occurs from ultraviolet radiation or certain chemicals, this protein then aids in repairing the damage.
RAD51 directly interacts with XRCC3, which is a protein that helps RAD51 bind more strongly to the broken strands of DNA; XRCC5, which is another protein RAD51 relies on for strand alignment; CDK6, which prevents the cell from committing suicide when it detects a chromosome break; and PARP1, which repairs damage caused by radiation exposure.
RAD51 consists of two alpha-helices and three beta-strands. This is an important structure as it assists in DNA repair. It does this by binding to both single-stranded and double-stranded DNA molecules and then interacting with other proteins to form a helicase which unwinds the DNA for repair.
While its mechanism isn't fully understood, it is thought that to deal with breaks and other errors in our DNA, since we have cells that are constantly searching for a way to fix them. When they find one, they move on it quickly, like a band-aid pulled off quickly or a zipper unzipped quickly. There are two different types of errors that can be repaired: insertion/deletion loops and nucleotide mismatches - which can be thought of as broken.