Developmentally regulated transcription factor AP-1 binds and recognizes the enhancer DNA sequence: 5'-TGA[CG]TCA-3'. May play a role in the function or determination of a particular subset of cells in the developing embryo. It is able to carry out its function either independently of or in conjunction with Jra (By similarity). Homodimer. Heterodimer with Jra. The kay-Jra heterodimer binds more stably to the AP-1 site than either of the two proteins alone (By similarity). Belongs to the bZIP family. Fos subfamily.