CED-3 cleaves IFG-1 p170 at Aspartate 456.

(A) Diagram of full length IFG-1 depicting the rCED-3 cleavage region between amino acids 420 and 686. No canonical caspase 3 recognition sites (DXXD) are present in this region. The positions of the non-canonical caspase cleavage sites (XXXD) are shown. (B) and (C) Aspartates 427 and 456 were mutated to alanines in the context of full length IFG-1 (1–1156). Radiolabeled IFG-1 (1–1156) was incubated with either (B) C. elegans rCED-3 or (C) human rCasp-3, resolved by SDS-PAGE, and visualized by phosphorimaging. The (*) indicates processed fragments and a carrot (<) represents the absence of a processed fragment. IFG-1 D456A was resistant to cleavage by rCED-3, and abolished one of the two cleavages by rCasp-3.