Skip to main content
. Author manuscript; available in PMC: 2013 Dec 6.
Published in final edited form as: Cell. 2013 May 30;153(6):1266–1280. doi: 10.1016/j.cell.2013.05.023

Figure 7. PTIP and RIF1 association with DSBs is dependent on distinct phosphorylation sites on 53BP1.

Figure 7

(A) 53BP1−/− MEFs (reconstituted with 53BP1DB, 53BP18A, 53BP17A, or 53BP115A were co-stained with RIF1 (red) and PTIP (green). Scale bar represents 10 μm. (B) Quantitation of percent 53BP1DB, 53BP18A, 53BP17A or 53BP115A cells with greater than ten 53BP1, PTIP or RIF1 foci. At least 100 cells were analyzed for each genotype. (C) Integrated intensity of individual IRIF in 53BP1−/− MEFs reconstituted with DB or 7A. Average RIF1 foci intensity (red line) is 1.6 fold greater in DB vs. 7A (** p<0.001, one-tailed unpaired t-test), and a greater percentage of very intense foci (z-score>3) are generated in 53BP1DB compared to 53BP17A (blue box). (D) Model for regulation of 53BP1 pro-NHEJ and anti-HR activities by distinct phospho-interactions with RIF1 and PTIP respectively. PTIP binds to the 8S/TQ sites. RIF1 recruitment is largely dependent on C-terminal 7S/TQ sites, but RIF1 may also be stabilized by interactions with 8S/TQ. An unknown factor (X) may bind directly to phosphorylated 53BP1 and mediate RIF1 recruitment, whereas PTIP interaction with 53BP1 is direct (Munoz et al., 2007). See also Figures S11-S13.