CIDE_N domain of CIDE-A proteins. The CIDE_N (cell death-inducing DFF45-like effector, N-terminal) domain is found at the N-terminus of the CIDE (cell death-inducing DFF45-like effector) proteins. 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 the CAD/DFF40, ICAD/DFF45, and CIDE nucleases during apoptosis. The CIDE protein family includes 3 members: CIDE-A, CIDE-B, and FSP27(CIDE-C). Based on sequence similarity with DFF40 and DFF45, the CIDE proteins were initially characterized as mitochondrial activators of apoptosis. However, strong metabolic phenotypes of mice lacking CIDE-A and CIDE-B indicated that this family may play critical roles in energy balance.