Transcription factor involved in regulating gene activity following the primary growth factor response. Binds to the DNA sequence 5'-TGA[GC]TCA-3' (By similarity). Heterodimerizes with proteins of the FOS family to form an AP-1 transcription complex, thereby enhancing its DNA binding activity to an AP-1 consensus sequence and its transcriptional activity (By similarity). Binds DNA as a homodimer or as a heterodimer with another member of the Jun/Fos family (By similarity). Component of an AP-1 transcription factor complex composed of JUN-FOS heterodimers (By similarity). As part of the AP-1 transcription factor complex, forms heterodimers with FOSB, thereby binding to the AP-1 consensus sequence and stimulating transcription (By similarity). Interacts with ITCH (via its WW domains) (By similarity). Ubiquitinated by ITCH, leading to its degradation. Belongs to the bZIP family. Jun subfamily.