Sequence alignment of N-terminals for Cide and Dff family proteins in hydra, sea anemone, and human. Shown here are six N-terminals of Cide and Dff proteins, with the sequence from human Cideb representing the CIDE-N domain and the rest representing the NCD domains. The most conserved EDGT signature is highlighted in red. The RPXRV signature of Cide family proteins is highlighted in yellow, the VDDXXYF signature of Dffa in purple, and the LPXXGSR signature of Dffb in green. The exon boundaries are marked by black vertical lines. The potential exon boundaries are marked by black dotted lines. The secondary structure of the human Cideb's CIDE-N domain is presented on the top of the alignment ; cylinders and arrows represent α helices and β strands, respectively.