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. 2017 Dec 22;28(2):143–156. doi: 10.1038/cr.2017.158

Figure 4.

Figure 4

Activation of ATR by TopBP1. (A) Potential TopBP1 binding sites. Two different views of ATR dimer are shown with key residues and PRD region for TopBP1 association indicated. Note that T1989 is located away from both catalytic cavities, suggesting a trans-mode autophsophorylation. (B) The AAD domain (residues 978-1 192) of TopBP1 is sufficient for ATR activation. ATR-ATRIP (10 nM) complex was preincubated with various truncations of TopBP1 before adding 3.5 μM Chk1 for reaction. The TopBP1 protein concentration used for reaction are: FL (50 nM), 1-978 (230 nM), 978-1 192 (625 nM), 1 192-1 522 (1.4 μM), 978-1 522 (1.0 μM). Note that 5 μl and 20 μl of reaction products were subjected to SDS-PAGE for immunoblotting and Coomassie blue staining, respectively. The positions of various TopBP1 proteins were indicated as star.