Nine novel conserved motifs in BRCA1 identified by the chicken orthologue

The breast cancer susceptibility gene BRCA1 encodes a multifunctional prote in that is mutated in many hereditary breast and ovarian cancers. We have c loned a homologue of the human BRCA1 gene from chicken; the gene encodes a 1749 amino acid protein that is 33% identical to human BRCA1, Phylogenetic analyses of the chicken and mammalian proteins indicate that the chicken ge ne is a bona fide BRCA1 orthologue, the first to be described from a non-ma mmal. Most of the chicken protein has diverged considerably from its mammal ian orthologues, although the RING and BRCT repeat regions are highly conse rved. This marked overall sequence divergence has allowed us to identify ni ne additional highly-conserved motifs (ranging from 8-56 amino acids in len gth) which are likely important for BRCA1 function.