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Configuration
of a DNA-binding protein that resembles a finger
with a base, usually cysteines and histidines, binding
a zinc ion. Discovered in a transcription factor
in Xenopus but present in a large number of different
proteins.
Below is from http://www.biochem.ucl.ac.uk/bsm/prot_dna/family_descriptions/zincfinger_family/zincfinger_family.html
Characteristics of the family:
- Function: The DNA-binding motif is
found as part of transcription regulatory proteins.
- Structure: One of the most abundant
DNA-binding motifs. Proteins may contain more
than one finger in a single chain; each motif
consists of 2 antiparallel beta-strands followed
by by an alpha-helix. A single zinc ion is tetrahedrally
coordinated by conserved histidine and cysteine
residues, stabilising the motif.
- Binding: Fingers bind to 3 base-pair
subsites and specific contacts are mediated
by amino acids in positions -1, 2, 3 and 6 relative
to the start of the alpha-helix. Contacts mainly
involve one strand of the DNA.
Where proteins contain multiple fingers, each
finger binds to adjacent subsites within a larger
DNA recognition site thus allowing a relatively
simple motif to specifically bind to a wide
range of DNA sequences.
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