Part:BBa_K4905005

Basic-region Leucine zippers (bZIPs) are alpha-helical domains with a repeating unit “abcdefg”. In this unit, the positions “a” and “d” consist of a hydrophobic residue and the ”e” and “g” positions consist of charged residues. The zippers form an alpha-helix and their charged residues form ion pairs between helices, causing them to associate(Alber, 1992).

Individual bZIP proteins can form homodimers or heterodimers with other bZIP proteins with a slightly different sequence(Alber, 1992) Not all bZIP proteins can dimerize with each other, some will only homodimerize with the same bZIP protein. Others will only heterodimerize with specific other bZIP proteins(Hakoshima, n.d.).

In cells, the main function of bZIPs is that they work as transcription factor, where the homodimer or heterodimer will form at the promotor regions of target genes (Seldeen et al., 2010). This makes leucine zippers a large family of transcription factors, where each member has a preference for a specific DNA sequence (Hakoshima, n.d.).

The TU-Eindhoven 2023 team used this part in a composite part for the formation of a hydrogel in e.coli. Two different bZIP proteins are made, which will form a heterodimer. This part is one of these bZIP proteins.