The WD β-propellers of Atg16L1 directly interact with Ub. (A) HeLa cells were lysed with 1% Triton X-100 lysis buffer and subjected to immunoprecipitation with FK2- or control IgG-immobilized beads. The coimmunoprecipitated molecules were examined by Western blotting using the indicated antibodies. (B) Schematic diagram of Atg16L1 (Full) and its deletion constructs. (C) Purified recombinant GST or GST-Ub–immobilized glutathione Sepharose beads were incubated with lysates from HEK293T cells transiently expressing FLAG-tagged Atg16L1 constructs for 1 h at 25°C with gentle agitation. The beads were washed three times with ice-cold PBS and the bound complexes were eluted with 50 mM reduced glutathione and then subjected to Western blotting for FLAG. (D) Purified GST or GST-Ub–immobilized glutathione Sepharose beads were incubated with lysates from bacteria expressing trigger factor (TF) or TF-FLAG-WD β-propellers for 1 h at 25°C with gentle agitation. Washing and elution were performed as described in C. The eluted samples were subjected to SDS-PAGE and Western blotting for FLAG.