RAD51

DNA repair protein RAD51 homolog 1 is a protein encoded by the gene RAD51. The enzyme encoded by this gene is a member of the RAD51 protein family which assists in repair of DNA double strand breaks. RAD51 family members are homologous to the bacterial RecA, Archaeal RadA, and yeast Rad51. The protein is highly conserved in most eukaryotes, from yeast to humans.

The name RAD51 derives from radiation sensitive protein 51.

Two alternatively spliced transcript variants of this gene have been reported, which encode distinct proteins. Transcript variants utilizing alternative polyA signals also exist.

In mammals, seven recA-like genes have been identified: Rad51, Rad51L1/B, Rad51L2/C, Rad51L3/D, XRCC2, XRCC3, and DMC1/Lim15. All of these proteins, with the exception of meiosis-specific DMC1, are essential for development in mammals. Rad51 is a member of the RecA-like NTPases.

In humans, RAD51 is a 339-amino acid protein that plays a major role in homologous recombination of DNA during double strand break repair. In this repair process, an ATP-dependent DNA strand exchange takes place in which a template strand invades base-paired strands of homologous DNA molecules. RAD51 is involved in the search for homology and strand pairing stages of the process.

Unlike other proteins involved in DNA metabolism, the RecA/Rad51 family forms a helical nucleoprotein filament on DNA.

This protein can interact with the ssDNA-binding protein RPA, BRCA2, PALB2 and RAD52.

The structural basis for Rad51 filament formation and its functional mechanism still remain poorly understood. However, recent studies using fluorescent labeled Rad51 have indicated that Rad51 fragments elongate via multiple nucleation events followed by growth, with the total fragment terminating when it reaches about 2 μm in length. However, disassociation of Rad51 from dsDNA is slow and incomplete, suggesting that there is a separate mechanism that accomplishes this.