The BRCA1 Breast Cancer Suppressor: Regulation of Transport, Dynamics, and Function at Multiple Subcellular Locations

Figure 5

BRCA1 exists in dynamic and immobile states at the centrosome. The mobility of BRCA1 has been examined at the centrosome by FRAP assay. As shown (top panel), images of transiently expressed YFP-BRCA1 in MCF-7 cells reveal a rapid recovery of BRCA1 fluorescence within 20 seconds after photobleaching at the centrosome (adapted from Brodie and Henderson [46]). In contrast, bleaching of the carboxy-terminal fragment of centrosomal pericentrin (tagged with RFP) recovered to a lesser extent. Quantification of fluorescence recovery is shown in the graph (lower panel), revealing that ~40% of wild-type YFP-BRCA1 is immobile at the centrosome, whereas ~60% is under dynamic exchange. Note that an internal deleted form of BRCA1 (N304 + C243), that lacks the two recently described gamma-tubulin binding sites [104], displays a moderately faster rate of recovery after bleaching, suggesting that interaction with gamma-tubulin contributes to some of the transient interactions between BRCA1 and centrosome. These data were originally published in Brodie and Henderson [46], ©  the American Society for Biochemistry and Molecular Biology, and reproduced with permission.