In Saccharomyces cerevisiae the Rad9 a key adaptor protein in DNA damage checkpoint pathways. DNA damage induces Rad9 phosphorylation, and Rad53 specifically associates with this region of Rad9, when phosphorylated, via Rad53 Pfam:PF00498 domains [1]. This region is structurally composed of a pair of TUDOR domains [1].

1: The FHA domain is a modular phosphopeptide recognition motif. Durocher D, Henckel J, Fersht AR, Jackson SP; Mol Cell. 1999;4:387-394. PMID:10518219

2: The checkpoint Saccharomyces cerevisiae Rad9 protein contains a tandem tudor domain that recognizes DNA. Lancelot N, Charier G, Couprie J, Duband-Goulet I, Alpha-Bazin B, Quemeneur E, Ma E, Marsolier-Kergoat MC, Ropars V, Charbonnier JB, Miron S, Craescu CT, Callebaut I, Gilquin B, Zinn-Justin S; Nucleic Acids Res. 2007;35:5898-5912. PMID:17726056