Fig. 2. Caspase-2 CARD can be solubilized by its binding partner, RAIDD CARD, but not by full-length RAIDD. (A) His-tag pull-down assay of caspase-2 CARD with RAIDD CARD. RAIDD CARD with His-tag and caspase-2 CARD without His-tag were co-expressed. Co-eluted caspase-2 CARD is shown. Lane 1, marker; Lane 2, supernatant of the cell lysate; Lane 3, pellet of the cell lysate; Lane 4, flow through after incubation with Ni-NTA beads; Lanes 5 and 6, washing; Lanes 7-8, imidazole eluted fraction. (B) Fractions from a pull-down assay containing RAIDD CARD and co-eluted caspase-2 CARD were subjected to gel filtration chromatography. The peak fractions (black bar) were loaded onto SDS-PAGE. (C) His-tag pull-down assay for caspase-2 CARD with full-length RAIDD. Full-length RAIDD with His-tag and caspase-2 CARD without His-tag were co-expressed. Lane 1, marker; Lane 2, supernatant of the cell lysate; Lane 3, pellet of the cell lysate; Lane 4, flow through after incubation with Ni-NTA beads; Lanes 5 and 6, washing; Lanes 7-8, imidazole eluted fractions. (D) Fractions from pull-down assay containing full-length RAIDD and co-eluted caspase-1 CARD were subjected to gel filtration chromatography. The peak fractions (black bar) were subjected to SDS-PAGE.