Enables DNA-binding transcription factor activity, RNA polymerase II-specific; enzyme binding activity; and mitochondrial transcription factor activity. Involved in several processes, including mitochondrial unfolded protein response; positive regulation of nematode larval development; and regulation of gene expression. Located in mitochondrial matrix and nucleus. Human ortholog(s) of this gene implicated in prostate carcinoma. Is an ortholog of human ATF4 (activating transcription factor 4).