{PDOC51915}
{PS51915; ZAD}
{BEGIN}
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* ZAD domain profile *
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C2H2 zinc-finger  (ZF)  motifs  (see  <PDOC00028>),  which  represent the most
abundant nucleic  acid  binding  motif in higher eukaryotes, are found in RNA-
binding proteins,  transcription  factors  and chromatin components. C2H2 zinc
finger proteins  frequently  contain  additional  protein  modules in their N-
termini. The zinc finger-associated domain (ZAD) is found at the N-terminus of
the C2H2  proteins  of  many  arthropods [1]. In vertebrates, only one protein
containing an  N-terminal structure similar to the ZAD has been found, ZFO276.
The ZAD-coding  genes  are  subject  to  an ongoing lineage-specific expansion
(LSE), which is most pronounced in the higher holometabolous insects. The ZAD
is a protein-protein interaction module with the capability to form
homodimers [2,3].

The ZAD  size  varies  between  71  and  97  amino  acids and consists of four
conserved blocks  linked  by  regions of varying lengths. The structure of the
ZAD domain  resembles  that  of  a treble-cleft fold and is stabilized by zinc
coordination via four cysteine residues found  to be invariably present in all
identified ZAD  peptides  (see <PDB:1PZW>). The N-terminal ZAD portion forms a
globule around  the  zinc  ion,  and  the  C-terminal stem is formed by a long
alpha-helix that comprises almost one-third of all amino acids in the ZAD. Two
ZAD molecules  are  associated  as an antiparallel dimer and most of the amino
acid residues  that  are conserved in the ZAD family form contacts between the
two subunits [4].

The profile we developed covers the entire ZAD domain.

-Sequences known to belong to this class detected by the profile: ALL.
-Other sequence(s) detected in Swiss-Prot: NONE.
-Last update: February 2020 / First entry.

[ 1] Chung H.-R., Schaefer U., Jaeckle H., Boehm S.
     "Genomic expansion and clustering of ZAD-containing C2H2 zinc-finger
     genes in Drosophila."
     EMBO. Rep. 3:1158-1162(2002).
     PubMed=12446571; DOI=10.1093/embo-reports/kvf243
[ 2] Chung H.-R., Loehr U., Jaeckle H.
     "Lineage-specific expansion of the zinc finger associated domain
     ZAD."
     Mol. Biol. Evol. 24:1934-1943(2007).
     PubMed=17569752; DOI=10.1093/molbev/msm121
[ 3] Fedotova A.A., Bonchuk A.N., Mogila V.A., Georgiev P.G.
     "C2H2 Zinc Finger Proteins: The Largest but Poorly Explored Family of
     Higher Eukaryotic Transcription Factors."
     Acta Naturae. 9:47-58(2017).
     PubMed=28740726
[ 4] Jauch R., Bourenkov G.P., Chung H.-R., Urlaub H., Reidt U., Jaeckle H.,
     Wahl M.C.
     "The zinc finger-associated domain of the Drosophila transcription
     factor grauzone is a novel zinc-coordinating protein-protein
     interaction module."
     Structure 11:1393-1402(2003).
     PubMed=14604529; DOI=10.1016/j.str.2003.09.015

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