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Tuesday 24 August 2004

zinc finger domain proteins

Zinc finger proteins have been shown to interact with nucleic acids and to have diverse functions, such as stimulation of transcription, transcriptional repression, binding to single-stranded DNA, binding to RNA, or bifunctional DNA- and RNA-binding activities.


ZNF44 ZNF217 ZNF384 ZNF674

The zinc finger domain is a conserved amino acid sequence motif containing 2 specifically positioned cysteines and 2 histidines that are involved in coordinating zinc. Zinc fingers bind divalent zinc ions by 1 of at least 5 different combinations of cysteines and histidines, including the eukaryotic C2H2, C4, and C6 motifs.

The Drosophila protein Kruppel belongs to a very large family of related C2H2 zinc finger proteins in which the zinc finger motifs are located in smaller or larger tandem arrays.

The spacer region connecting successive zinc finger repeats, known as the H/C link, is highly conserved among members of this family, showing a higher degree of homology than the finger motif. Structurally conserved motifs outside the zinc finger regions subdivide the Kruppel family into smaller subfamilies.

One such motif is the Kruppel-associated box (KRAB), which is an approximately 75-amino acid domain that is usually positioned in the N terminus of the protein and which may form a leucine zipper-like structure.