CIDE_N domain of CAD nuclease. The CIDE_N (cell death-inducing DFF45-like effector, N-terminal) domain is found at the N-terminus of CAD nuclease (caspase-activated DNase/DNA fragmentation factor, DFF40) and its inhibitor, ICAD(DFF45). These proteins are associated with the chromatin condensation and DNA fragmentation events of apoptosis; the CIDE_N domain is thought to regulate the activity of CAD/DFF40 and ICAD/DFF45 during apoptosis. In normal cells, DFF exists in the nucleus as a heterodimer composed of CAD/DFF40 as a latent nuclease and its chaperone and inhibitor subunit ICAD/DFF45. Apoptotic activation of caspase-3 results in the cleavage of DFF45/ICAD and the release of active DFF40/CAD nuclease.