The Basic Leucine Zipper Domain (bZIP domain) is found in many DNA binding eukaryotic proteins. One part of the domain contains a region that mediates sequence specific DNA binding properties and the leucine zipper that is required to hold together (dimerize) two DNA binding regions. The DNA binding region comprises a number of basic amino acids such as arginine and lysine. Proteins containing this domain are transcription factors.

bZIP transcription factors are found in all eukaryotes and form one of the largest families of dimerizing TFs. An evolutionary study from 2008 revealed that 4 bZIP genes were encoded by the genome of the most recent common ancestor of all plants. Interactions between bZIP transcription factors are numerous and complex and play important roles in cancer development in epithelial tissues, steroid hormone synthesis by cells of endocrine tissues, factors affecting reproductive functions, and several other phenomena that affect human health.

ATF1; ATF2; ATF4; ATF5; ATF6; ATF7; BACH1; BACH2; BATF; BATF2; CEBPA; CEBPB; CEBPD; CEBPE; CEBPG; CEBPZ; CREB1; CREB3; CREB3L1; CREB3L2; CREB3L3; CREB3L4; CREB5; CREBL1; CREM; E4BP4; FOSL1; FOSL2; JUN; JUNB; JUND; MAFA; MAFB; MAFF; MAFG; NRL; C-MAF; MAFK; NFE2; NFE2L2; NFE2L3; SNFT; XBP1