{PDOC00036}
{PS00036; BZIP_BASIC}
{PS50217; BZIP}
{BEGIN}
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* Basic-leucine zipper (bZIP) domain signature and profile *
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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 [3].

Several  structure  of bZIP have been solved (see for example <PDB:1AN2>) [4].
The  basic  region and the leucine zipper form a contiguous alpha 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)
   oncogene v-jun.
 - Jun-B and jun-D,  probable transcription factors which  are  highly similar
   to jun/AP-1.
 - The fos protein, a  proto-oncogene  that  forms  a  non-covalent dimer with
   c-jun.
 - 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
   protein genes.
 - 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
   protein.
 - 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.

-Consensus pattern: [KR]-x(1,3)-[RKSAQ]-N-{VL}-x-[SAQ](2)-{L}-[RKTAENQ]-x-R-
                    {S}-[RK]
-Sequences known to belong to this class detected by the profile: the    large
 majority.
-Other sequence(s) detected in Swiss-Prot: 18.

-Sequences known to belong to this class detected by the profile: ALL.
-Other sequence(s) detected in Swiss-Prot: NONE.

-Last update: April 2006 / Pattern revised.

[ 1] Hurst H.C.
     Protein Prof. 2:105-168(1995).
[ 2] Ellenberger T.
     Curr. Opin. Struct. Biol. 4:12-21(1994).
[ 3] Baranger A.M.
     "Accessory factor-bZIP-DNA interactions."
     Curr. Opin. Chem. Biol. 2:18-23(1998).
     PubMed=9667910
[ 4] Ferre-D'amare A.R., Prendergast G.C., Ziff E.B., Burley S.K.
     Nature 363:38-45(1993).
[ 5] Ellenberger T.E., Brandl C.J., Struhl K., Harrison S.C.
     "The GCN4 basic region leucine zipper binds DNA as a dimer of
     uninterrupted alpha helices: crystal structure of the protein-DNA
     complex."
     Cell 71:1223-1237(1992).
     PubMed=1473154

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