Zinc finger
234129
225682775
2008-07-14T21:50:30Z
Boghog2
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[[Image:Zinc finger rendered.png|thumb|300px|right|Cartoon representation of the zinc finger motif of proteins, consisting of an [[alpha helix|α helix]] and an antiparallel [[Beta_sheet|β sheet]]. The [[zinc]] ion (green) is coordinated by two [[histidine]] residues and two [[cysteine]] residues.]]
[[Image:Zinc finger DNA complex.png|thumb|300px|right|Cartoon representation of the protein [[Zif268]] (blue) containing three zinc fingers in complex with DNA (orange). The coordinating amino acid residues of the middle zinc ion (green) are highlighted.]]
A '''zinc finger''' is a large superfamily of [[protein domain]]s that can bind to [[DNA]]. A zinc finger consists of two [[antiparallel]] [[Beta_strand|β strands]], and an [[alpha helix|α helix]]. The [[zinc]] ion is crucial for the stability of this domain type - in the absence of the metal ion the domain unfolds as it is too small to have a [[hydrophobic core]].
==Classes==
One very well explored subset of zinc-fingers (the C<sub>2</sub>H<sub>2</sub> class) comprises a pair of [[cysteine]] residues in the beta strands and two [[histidine]] residues in the alpha helix which are responsible for binding a zinc ion. The two other classes of zinc finger proteins are the C<sub>4</sub> and C<sub>6</sub> classes. Zinc fingers are important in regulation because when interacted with DNA and zinc ion, they provide a unique [[structural motif]] for [[DNA#DNA-binding_proteins|DNA-binding proteins]].
==Structure==
The structure of each individual finger is highly [[Conservation (genetics)|conserved]] and consists of about 30 [[amino acid]] residues, constructed as a ββα fold and held together by the zinc ion. The α-helix occurs at the C-terminal part of the finger, while the β-sheet occurs at the N-terminal part.
The [[consensus sequence]] of a single finger is:
Cys-X<sub>2-4</sub>-Cys-X<sub>3</sub>-Phe-X<sub>5</sub>-Leu-X<sub>2</sub>-His-X<small>3</small>-His
==Proteins with Zinc finger==
Many [[transcription factor]]s (such as [[Zif268]]), regulatory proteins, and other proteins that interact with DNA contain zinc fingers. These proteins typically interact with the major groove along the double [[helix]] of DNA in which case the zinc fingers are arranged around the DNA strand in such a way that the α-helix of each finger contacts the DNA, forming an almost continuous stretch of α-helices around the DNA molecule.
Some primary neuron-specific transcriptional regulator that may be involved in mediating early neural development are also zinc finger-based.
==Binding specificity==
The binding specificity for 3–4 [[base pair]]s is conferred by a short stretch of amino acid residues in the α-helix. The primary position of the amino acid residues within the α-helix interacting with the DNA are at positions -1, 3 and 6 relative to the first amino acid residue
of the α-helix. Other amino acid positions can also influence binding specificity by assisting amino acid residues to bind a specific base
or by contacting a fourth base in the opposite strand, causing target-site overlap.
== See also ==
* [[Zinc finger inhibitor]]
* [[Steroid hormone receptor]]
== References ==
{{cite journal
| last = Luscombe
| first = Nicholas, ''et al''
| title = An overview of the structures of protein-DNA complexes
| journal = Genome Biology Review
| volume = 1
| issue = 1
| pages = 4–5
| date = 9 June 2000
| doi = 10.1186/gb-2000-1-1-reviews001
}}
== External links ==
* {{ cite web | url= http://www.ebi.ac.uk/interpro/potm/2007_3/Page1.htm | title= Protein of the Month: Zinc Fingers|accessdate= 2008-01-13 | author= McDowall J | publisher= European Molecular Biology Laboratory - European Bioinformatics Institute (EMBL-EBI) }}
* {{ cite web | url= http://www.rcsb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/pdb87_1.html | title= Molecule of the Month: Zinc Fingers|accessdate= 2008-01-13 | author= Goodsell DS | publisher= Research Collaboratory for Structural Bioinformatics (RCSB) Protein Data Bank (PDB) }}
* [http://www.zincfingertools.org Zinc Finger Tools design and information site]
* [http://znf.llnl.gov/catalog/ Human KZNF Gene Catalog]
* [http://www.expasy.org/cgi-bin/nicedoc.pl?PDOC00028 Zinc finger C2H2-type domain] in [[PROSITE]]
* [http://smart.embl-heidelberg.de/smart/do_annotation.pl?DOMAIN=ZnF_C2H2 Entry for zinc finger class C2H2 in the SMART database]
* [http://www.zincfingers.org The Zinc Finger Consortium]
* [http://bindr.gdcb.iastate.edu/ZiFiT/ ZiFiT- Zinc Finger Design Tool]
* [http://www.addgene.org/zfc Zinc Finger Consortium Materials from Addgene]
{{Protein domains}}
{{Transcription factors|g2}}
[[Category:Protein domains]]
[[Category:Protein structural motifs]]
[[Category:Protein folds]]
[[ca:Dit de zinc]]
[[de:Zinkfingerprotein]]
[[it:Dito di zinco]]
[[ja:ジンクフィンガー]]
[[pl:Palec cynkowy]]
[[pt:Dedo de zinco]]
[[fi:Sinkkisormi]]
[[zh:锌指结构]]