The bZIP superfamily [1,2] of eukaryotic DNA-binding transcription factors
groups together proteins that contain a basic region mediating sequence-specific DNA-binding followed by a leucine zipper (see <PDOC00029>) required
for dimerization. bZIP domains usually bind a palindromic 6 nucleotide site,
but the specificity can be altered by interaction with accessory factor .
Several structure of bZIP have been solved (see for example <PDB:1AN2>) .
The basic region and the leucine zipper form a contiguous α helice where
the four hydrophobic residues of the leucine zipper are oriented on one side.
This conformation allows dimerization in parallel and it bends the helices so
that the newly functional dimer forms a flexible fork where the basic domains,
at the N-terminal open end, can then interact with DNA. The two leucine zipper
are therefore oriented perpendicular to the DNA [4,5].
This family is quite large and we only list here some representative members.
Transcription factor AP-1, which binds selectively to enhancer elements in
the cis control regions of SV40 and metallothionein IIA. AP-1, also known
as c-jun, is the cellular homolog of the avian sarcoma virus 17 (ASV17)
Jun-B and jun-D, probable transcription factors which are highly similar
The fos protein, a proto-oncogene that forms a non-covalent dimer with
The fos-related proteins fra-1, and fos B.
Mammalian cAMP response element (CRE) binding proteins CREB, CREM, ATF-1,
ATF-3, ATF-4, ATF-5, ATF-6 and LRF-1.
Maize Opaque 2, a trans-acting transcriptional activator involved in the
regulation of the production of zein proteins during endosperm.
Arabidopsis G-box binding factors GBF1 to GBF4, Parsley CPRF-1 to CPRF-3,
Tobacco TAF-1 and wheat EMBP-1. All these proteins bind the G-box promoter
elements of many plant genes.
Drosophila protein Giant, which represses the expression of both the
kruppel and knirps segmentation gap genes.
Drosophila Box B binding factor 2 (BBF-2), a transcriptional activator that
binds to fat body-specific enhancers of alcohol dehydrogenase and yolk
Drosophila segmentation protein cap'n'collar (gene cnc), which is involved
in head morphogenesis.
Caenorhabditis elegans skn-1, a developmental protein involved in the fate
of ventral blastomeres in the early embryo.
Yeast GCN4 transcription factor, a component of the general control system
that regulates the expression of amino acid-synthesizing enzymes in
response to amino acid starvation, and the related Neurospora crassa cpc-1
Neurospora crassa cys-3 which turns on the expression of structural genes
which encode sulfur-catabolic enzymes.
Yeast MET28, a transcriptional activator of sulfur amino acids metabolism.
Yeast PDR4 (or YAP1), a transcriptional activator of the genes for some
oxygen detoxification enzymes.
Epstein-Barr virus trans-activator protein BZLF1.
The pattern we developped is directed against the basic region. We also
developed a profile that covers the whole domain.
April 2006 / Pattern revised.
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