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. 2000 May 2;97(10):5208–5213. doi: 10.1073/pnas.080469697

Figure 5.

Figure 5

Identification of the STAT1-binding segment of BRCA1. Six GST-BRCA1 fusion proteins (aa 1–324; 260–553; 502–802; 758–1,064; 1,005–1,313; and 1,314–1,863) were generated in E. coli, and used for an in vitro binding assay (from lanes 4 to 9, respectively). GST protein alone was used for lane 3. Approximately equal amounts of each GST-fusion protein, bound to glutathione-Sepharose beads, were incubated with an extract of IFN-γ-treated (10 ng/ml, 15 min) 293T cells. Bound proteins were recovered and separated electrophoretically. Total lysate (20 μg) was loaded as a control (lane 1). Lane 2 contains no protein. The separated proteins were immunoblotted for STAT1. This STAT1 antiserum recognizes a 91-kDa (STAT1α), not 84-kDa (STAT1β), protein bound to GST-BRCA1 (aa 502–802) in lane 6, showing that STAT1α specifically binds to BRCA1.