{PDOC00564}
{PS00657; FORK_HEAD_1}
{PS00658; FORK_HEAD_2}
{PS50039; FORK_HEAD_3}
{BEGIN}
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* Fork head domain signatures and profile *
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It has been shown [1]  that  some  eukaryotic  transcription factors contain a
conserved  domain of    about  100  amino-acid  residues, called the fork head
domain (but also known as a "winged helix"), which is  involved in DNA-binding
[2]. Proteins known to contain this domain are listed below.

 - Drosophila fork head protein (fkh). Fkh is probably a transcription  factor
   that regulates the expression of genes involved in terminal development.
 - Drosophila  protein  crocodile  (gene  croc) [3], which is required for the
   establishment of head structures.
 - Drosophila proteins FD2, FD3, FD4, and FD5.
 - Drosophila  proteins  sloppy  paired  1  and  2 (slp1 and slp2) involved in
   segmentation.
 - Bombyx  mori  silk  gland factor-1 (SGF-1) which regulates transcription of
   the sericim-1 gene.
 - Mammalian  transcriptional  activators  HNF-3-alpha, -beta, and -gamma. The
   HNF-3 proteins interact with the cis-acting  regulatory regions of a number
   of liver genes.
 - Mammalian  interleukin-enhancer  binding  factor  (ILF).  ILF  binds to the
   purine-rich NFAT-like  motifs  in  the  HIV-1  LTR  and  the  interleukin-2
   promoter.  ILF may be involved in both  positive and negative regulation of
   important viral and cellular promoter elements.
 - Mammalian  transcription  factor  BF-1 which plays an important role in the
   establishment  of  the regional subdivision of the developing brain and  in
   the development of the telencephalon.
 - Human HTLF, a protein that binds  to the purine-rich region in human T-cell
   leukemia virus long terminal repeat (HTLV-I LTR).
 - Mammalian  transcription  factors  FREAC-1 (FKHL5, HFH-8), FREAC-2 (FKHL6),
   FREAC-3 (FKHL7,  FKH-1),  FREAC-4  (FKHL8),  FREAC-5 (FKHL9, FKH-2, HFH-6),
   FREAC-6 (FKHL10,  HFH-5), FREAC-7 (FKHL11), FREAC-8 (FKHL12, HFH-7), FKH-3,
   FKH-4, FKH-5, HFH-1 and HFH-4.
 - Human  AFX1  which  is  involved in a chromosomal translocation that causes
   acute leukemia.
 - Human  FKHR  which  is  involved in a chromosomal translocation that causes
   rhabdomyosarcoma.
 - Xenopus XFKH1, a protein essential for normal axis formation.
 - Caenorhabditis  elegans  lin-31;  involved in the regulation of vulval cell
   fates.
 - Yeast HCM1, a protein of unknown function.
 - Yeast FKH1.
 - Yeast FKH2.

The fork domain is highly conserved.  We have  developed  two patterns for its
detection. The  first corresponds to the N-terminal section of the domain; the
second is a heptapeptide located in the central section of the domain.

-Consensus pattern: [KR]-P-[PTQ]-[FYLVQH]-S-[FY]-x(2)-[LIVM]-x(3,4)-[AC]-
                    [LIM]
-Sequences known to belong to this class detected by the pattern: ALL,  except
 for AFX1 and FKHR.
-Other sequence(s) detected in Swiss-Prot: NONE.

-Consensus pattern: W-[QKR]-[NSD]-[SA]-[LIV]-R-H
-Sequences known to belong to this class detected by the pattern: ALL.
-Other sequence(s) detected in Swiss-Prot: NONE.

-Last update: December 2004 / Pattern and text revised.

[ 1] Weigel D., Jaeckle H.
     "The fork head domain: a novel DNA binding motif of eukaryotic
     transcription factors?"
     Cell 63:455-456(1990).
     PubMed=2225060
[ 2] Clark K.L., Halay E.D., Lai E., Burley S.K.
     "Co-crystal structure of the HNF-3/fork head DNA-recognition motif
     resembles histone H5."
     Nature 364:412-420(1993).
     PubMed=8332212
[ 3] Haecker U., Kaufmann E., Hartmann C., Juergens G., Knoechel W.,
     Jaeckle H.
     EMBO J. 14:5306-5317(1995).

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