Product of the upstream open reading frame (uORF) of DDIT3/CHOP that is specifically produced in absence of stress, thereby preventing translation of downstream stress effector DDIT3/CHOP. Interacts with DDIT3 (isoform 1). Colocalizes with WDR83 in the cytoplasm. Produced in absence of stress: this uORF is translated, thereby preventing translation of downstream ORF, the stress effector DDIT3/CHOP (PubMed:21285359). This uORF is not translated in response to stress (PubMed:21285359). Product of the upstream open reading frame of this bicistronic gene.