4BU0:
reference: Phosphorylation-Dependent Assembly and Coordination of the DNA Damage Checkpoint Apparatus by Rad4(TopBP1.)., Qu M, Rappas M, Wardlaw CP, Garcia V, Ren JY, Day M, Carr AM, Oliver AW, Du LL, Pearl LH, Mol Cell. 2013 Sep 26;51(6):723-36. doi: 10.1016/j.molcel.2013.08.030. PMID: 24074952

This OCA Structure page
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