May be a general transcription factor that can form a stable complex with RNA polymerase II (By similarity). May prevent inappropriate targeting of non-secretory polypeptides to the endoplasmic reticulum (ER) (By similarity). In response to heat stress, plays a role in modulating the unfolded protein response by negatively regulating the accumulation of proteins such as the chaperone protein hsp-4 in the endoplasmic reticulum (PubMed:22957041). Required to suppress apoptosis in neuronal and intestinal cells to promote development (PubMed:12944970). May be part of the nascent polypeptide-associated complex (NAC), which is a heterodimer of icd-2 and icd-1 (via NAC-A/B domains). Expressed throughout development. RNAi-mediated knockdown mostly results in embryonic lethality, but embryos that do hatch produce larvae with a large number of apoptotic cell corpses, which are first present at the comma stage of development (PubMed:12944970). Surviving animals are uncoordinated (PubMed:12944970). RNAi-mediated knockdown results in increased neuronal and intestinal cell death and a reduced number of male tail rays in larvae (PubMed:12944970). RNAi-mediated knockdown in larvae results in increased survival and mobility in response to a constant temperature of 36 degrees Celsius, when compared to wild-type (PubMed:22957041). RNAi-mediated knockdown in adults results in embryos with severe morphological defects and high numbers of enlarged bi-refringent lipofuscin glo-1-positive granules in their gut cells, and increased cell death and degeneration (PubMed:22957041). These embryos also have increased expression of the endoplasmic reticulum-specific chaperone protein hsp-4 in regions of the embryo that contain gut and epithelial cells (PubMed:22957041). Belongs to the NAC-beta family.