Everything about Zinc Finger totally explained
A
zinc finger is a large superfamily of
protein domains that can bind to
DNA. A zinc finger consists of two
antiparallel β strands, and an
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's too small to have a
hydrophobic core.
Classes
One very well explored subset of zinc-fingers (the C
2H
2 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
4 and C
6 classes. Zinc fingers are important in regulation because when interacted with DNA and zinc ion, they provide a unique
structural motif for
DNA-binding proteins.
Structure
The structure of each individual finger is highly
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
2-4-Cys-X
3-Phe-X
5-Leu-X
2-His-X
3-His
Proteins with Zinc finger
Many
transcription factors (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 pairs 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.
vhy
Further Information
Get more info on 'Zinc Finger'.
|
External Link Exchanges
Do you know how hard it is to get a link from a large encyclopaedia? Well we're different and will prove it. To get a link from us just add the following HTML to your site on a relevant page:
<a href="http://zinc_finger.totallyexplained.com">Zinc finger Totally Explained</a>
Then simply click through this link from your web page. Our crawlers will verify your link, extract the title of your web page and instantly add a link back to it. If you like you can remove the words Totally Explained and embed the link in article text.
As long as your link remains in place, we'll keep our link to you right here. Please play fair - our crawlers are watching. Your site must be closely related to this one's topic. Any kind of spamming, dubious practises or removing the link will result in your link from us being dropped and, potentially, your whole site being banned. |
