The C. elegans cell death gene ced-3 encodes a protein similar to mammalian interleukin-1 beta-converting enzyme

We have cloned the C. elegans cell death gene ced-3. A ced-3 transcript is most abundant during embryogenesis, the stage during which most programmed cell deaths occur. The predicted CED-3 protein shows similarity to human and murine interleukin-1 beta-converting enzyme and to the product of the mouse nedd-2 gene, which is expressed in the embryonic brain. The sequences of 12 ced-3 mutations as well as the sequences of ced-3 genes from two related nematode species identify sites of potential functional importance. We propose that the CED-3 protein acts as a cysteine protease in the initiation of programmed cell death in C. elegans and that cysteine proteases also function in programmed cell death in mammals.