Ced-3 (also written CED‑3) is a cysteine‑aspartic protease—specifically, a caspase—that plays a central role in the execution of programmed cell death (apoptosis) in the nematode Caenorhabditis elegans. The protein is encoded by the ced‑3 gene, one of several genes identified in genetic screens for mutants defective in cell death. Activation of CED‑3 occurs downstream of the Apaf‑1–like adaptor protein CED‑4 and is negatively regulated by the anti‑apoptotic protein CED‑9. Once activated, CED‑3 cleaves a variety of cellular substrates, leading to the orderly dismantling of the cell.
Key characteristics:
- Structure: CED‑3 is synthesized as an inactive zymogen (procaspase) that undergoes proteolytic cleavage to generate a heterodimer composed of large (p17) and small (p12) subunits, which together form the active enzyme.
- Conservation: The catalytic domain of CED‑3 is conserved among metazoan caspases, providing a model for understanding the biochemical mechanisms of apoptosis across species.
- Genetic importance: Loss‑of‑function mutations in ced‑3 result in the survival of cells that normally undergo programmed death, producing characteristic developmental phenotypes in C. elegans embryos and larvae.
CED‑3 was first described in the mid‑1990s by researchers including H. R. Hengartner and Y. M. Miyaura, contributing to the broader elucidation of the conserved apoptotic pathway that includes mammalian caspases such as caspase‑3. The C. elegans apoptosis pathway—comprising CED‑9, CED‑4, and CED‑3—remains a foundational model in cell‑death biology.
