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QuickView for Zinc finger, C2HC-type (biogroup)
- Description:
- Zinc finger (Znf) domains are relatively small protein motifs which contain multiple finger-like protrusions that make tandem contacts with their target molecule. Some of these domains bind zinc, but many do not; instead binding other metals such as iron, or no metal at all. For example, some family members form salt bridges to stabilise the finger-like folds. They were first identified as a DNA-binding motif in transcription factor TFIIIA from Xenopus laevis (African clawed frog), however they are now recognised to bind DNA, RNA, protein and/or lipid substrates. 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. Zinc-binding motifs are stable structures, and they rarely undergo conformational changes upon binding their target. This entry represents the CysCysHisHisCys (CCHHC) type zinc finger domain found in eukaryotes. The CCHHC-type zinc finger contains five absolutely conserved cysteine and histidine residues (rather than the more usual four) with the sequence C-P-x-P-G-C-x-G-x-G-H-x(7)-H-R-x(4)-C. The second histidine has been shown to coordinate Zn(II) along with the three cysteines residues. The first His plays a different role in stabilizing the structure, stacking between the metal-binding core and an aromatic residue that is relatively conserved. CCHHC-type zinc fingers form small compact structures that can sit entirely within the major groove of DNA.Some proteins known to contain a CCHHC-type zinc finger are listed below:Animal myelin transcription factor 1 (MyT1), or neural zinc finger 2 (NZF2), a transcription factor that contains seven copies of the CCHHC-type zinc finger. It binds to sites in the proteolipid protein promoter.Vertebrate MyT1-like (MyT1L/NZF1), appears to be involved in neural development.Vertebrate Suppressor of Tumorigenicity 18 (ST18/NZF3), a breast cancer tumour suppressor.Vertebrate L3MBTL, a member of the Polycomb group of proteins, which function as transcriptional repressors in large protein complexes.Vertebrate L3MBTL3, a possible tumor suppressor.Vertebrate L3MBTL4.
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