BRCA1 ( /ˈbrækə/; breast cancer 1, early onset) is a human caretaker gene that produces a protein called breast cancer type 1 susceptibility protein, responsible for repairing DNA. The first evidence for the existence of the gene was provided by the King laboratory at UC Berkeley in 1990. The gene was later cloned in 1994 by scientists at Myriad Genetics.
BRCA1 is expressed in the cells of breast and other tissue, where it helps repair damaged DNA, or destroy cells if DNA cannot be repaired. If BRCA1 itself is damaged, damaged DNA is not repaired properly and this increases risks for cancers.
The protein encoded by the BRCA1 gene combines with other tumor suppressors, DNA damage sensors, and signal transducers to form a large multi-subunit protein complex known as the BRCA1-associated genome surveillance complex (BASC). The BRCA1 protein associates with RNA polymerase II, and through the C-terminal domain, also interacts with histone deacetylase complexes. Thus, this protein plays a role in transcription, DNA repair of double-stranded breaks ubiquitination, transcriptional regulation as well as other functions.