ZnF_C2H2

zinc finger		 ZnF_C2H2
SMART accession number:SM00355
Description:
Interpro abstract (IPR015880):

C2H2-type (classical) zinc fingers (Znf) were the first class to be characterised. They contain a short beta hairpin and an alpha helix (beta/beta/alpha structure), where a single zinc atom is held in place by Cys(2)His(2) (C2H2) residues in a tetrahedral array. C2H2 Znf's can be divided into three groups based on the number and pattern of fingers: triple-C2H2 (binds single ligand), multiple-adjacent-C2H2 (binds multiple ligands), and separated paired-C2H2 (PUBMED:11361095). C2H2 Znf's are the most common DNA-binding motifs found in eukaryotic transcription factors, and have also been identified in prokaryotes (PUBMED:10664601). Transcription factors usually contain several Znf's (each with a conserved beta/beta/alpha structure) capable of making multiple contacts along the DNA, where the C2H2 Znf motifs recognise DNA sequences by binding to the major groove of DNA via a short alpha-helix in the Znf, the Znf spanning 3-4 bases of the DNA (PUBMED:10940247). C2H2 Znf's can also bind to RNA and protein targets.

Zinc finger (Znf) domains are relatively small protein motifs that bind one or more zinc atoms, and which usually contain multiple finger-like protrusions that make tandem contacts with their target molecule. They were first identified as a DNA-binding motif in transcription factor TFIIIA from Xenopus laevis, however they are now recognised to bind DNA, RNA, protein and/or lipid substrates (PUBMED:10529348), (PUBMED:15963892), (PUBMED:15718139), (PUBMED:17210253), (PUBMED:12665246). Their binding properties depend on the amino acid sequence of the finger domains and of the linker between fingers, as well as on the higher-order structures and the number of fingers. Znf domains are often found in clusters, where fingers can have different binding specificities. There are many superfamilies of Znf motifs, varying in both sequence and structure. They display considerable versatility in binding modes, even between members of the same class (e.g. some bind DNA, others protein), suggesting that Znf motifs are stable scaffolds that have evolved specialised functions. For example, Znf-containing proteins function in gene transcription, translation, mRNA trafficking, cytoskeleton organisation, epithelial development, cell adhesion, protein folding, chromatin remodelling and zinc sensing, to name but a few (PUBMED:11179890). Zinc-binding motifs are stable structures, and they rarely undergo conformational changes upon binding their target.

(Note that in certain cases, some Znf domains have diverged such that they still maintain their core structure, but have lost their ability to bind zinc, using other means such as salt bridges or binding to other metals to stabilise the finger-like folds. These domains can show strong sequence identity to zinc-binding motifs, and may therefore be included in Znf entries).

This entry represents zinc finger domains resembling the C2H2-type.

More information about these proteins can be found at Protein of the Month: Zinc Fingers.

GO component:intracellular (GO:0005622)
GO function:zinc ion binding (GO:0008270)
Family alignment:
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There are 200049 ZnF_C2H2 domains in 29233 proteins in SMART's nrdb database.

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