The protein encoded by this gene is a basic leucine zipper (bZIP) transcription factor that lacks a transactivation domain. It is known to bind the US-2 DNA element in the promoter of the oxytocin receptor (OTR) gene and most likely heterodimerizes with other leucine zipper-containing proteins to enhance expression of the OTR gene during term pregnancy. The encoded protein can also form homodimers, and since it lacks a transactivation domain, the homodimer may act as a repressor of transcription. This gene may also be involved in the cellular stress response. Multiple transcript variants encoding two different isoforms have been found for this gene. [provided by RefSeq, Jun 2009].