Figure 5.

Variant sequences in the BRCA1 5′ region alter specific DNA:protein complex formation. Competition electrophoretic mobility shift assay (EMSAs) were performed using 3′ biotinylated double‐stranded DNA probes containing sequences from the BRCA1 5′ region surrounding the B1:c.‐315del (a and b) and B1:c.‐287C>T (c) variants. DNA probes containing the wild‐type (WT) or variant (Var) sequence were incubated with nuclear extracts from MCF7 cells (MCF7 NE) or MDA‐MB 468 cells (468 NE) in the presence (+) or absence (–) of unlabeled WT, Var, or nonspecific (NS) competitor (Comp) DNA. Free unbound probe (FP) and specific DNA:protein complexes (arrowheads) are indicated. Supershift experiments (d) were performed with the BRCA1:c.‐287C (WT) probe and antibodies to NFYA, Oct‐2 (POU2F2) and PAX5. The supershifted NFYA complex is indicated by asterisk (*)