{PDOC51523}
{PS51523; ZF_HD_DIMER}
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* Zinc-finger ZF-HD dimerization-type profile *
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The homeodomain  (HD)  is  a  60-amino  acid  DNA-binding domain found in many
transcription factors  (see  <PDOC00027>). HD-containing proteins are found in
diverse organisms  such  as  humans,  Drosophila,  nematode worms, and plants,
where they  play  important roles in development. Zinc-finger-homeodomain (ZF-
HD) subfamily  proteins  have  only been identified in plants, and likely play
plant specific   roles.   ZF-HD   proteins   are  expressed  predominantly  or
exclusively in  floral  tissue,  indicating  a  likely  regulatory role during
floral development  [1].  The  ZF-HD class of homeodomain proteins may also be
involved in  the  photosynthesis-related mesophyll-specific gene expression of
phosphoenolpyruvate carboxylase  in  C4  species [2] and in pathogen signaling
and plant defense mechanisms [3].

These proteins   share   three   domains  of  high  sequence  similarity:  the
homeodomain (II)  located  at the carboxy-terminus, and two other segments (Ia
and Ib)  located  in the amino-terminal part. These N-terminal domains contain
five conserved  cysteine  residues  and  at  least  three  conserved histidine
residues whose   spacing   ressembles   zinc-binding   domains   involved   in
dimerization of  transcription  factors.  Although  the two domains contain at
least eight  potential  zinc-binding  amino-acids,  the  unique spacing of the
conserved cysteine  and histidine residues within domain Ib suggests that both
domains form  one  rather  than  two zinc finger structures. The two conserved
motifs Ia  and Ib constitute a dimerization domain which is sufficient for the
formation of homo- and heterodimers [2].

The profile  we  developed  covers  the  entire  ZF-HD  dimerization-type zinc
finger.

-Sequences known to belong to this class detected by the profile: ALL.
-Other sequence(s) detected in Swiss-Prot: NONE.
-Last update: February 2011 / First entry.

[ 1] Tan Q.K.-G., Irish V.F.
     "The Arabidopsis zinc finger-homeodomain genes encode proteins with
     unique biochemical properties that are coordinately expressed during
     floral development."
     Plant Physiol. 140:1095-1108(2006).
     PubMed=16428600; DOI=10.1104/pp.105.070565
[ 2] Windhoevel A., Hein I., Dabrowa R., Stockhaus J.
     "Characterization of a novel class of plant homeodomain proteins that
     bind to the C4 phosphoenolpyruvate carboxylase gene of Flaveria
     trinervia."
     Plant Mol. Biol. 45:201-214(2001).
     PubMed=11289511
[ 3] Park H.C., Kim M.L., Lee S.M., Bahk J.D., Yun D.-J., Lim C.O.,
     Hong J.C., Lee S.Y., Cho M.J., Chung W.S.
     "Pathogen-induced binding of the soybean zinc finger homeodomain
     proteins GmZF-HD1 and GmZF-HD2 to two repeats of ATTA homeodomain
     binding site in the calmodulin isoform 4 (GmCaM4) promoter."
     Nucleic Acids Res. 35:3612-3623(2007).
     PubMed=17485478; DOI=10.1093/nar/gkm273

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