(c) Cytochrome c release assay. Truncated and full-length recombinant Atg5 were added to isolated mitochondria and incubated at 37 °C for 1 h. Supernatants and mitochondrial pellets were then analysed for cytochrome c by immunoblotting. Truncated Bid (tBid) was used as a positive control for mitochondrial permeabilization. Truncated Atg5 released cytochrome c in a concentration-dependent manner, indicating mitochondrial permeabilization. Full-length Atg5 had only little effect in this system. 