A number of C2H2-zinc finger proteins contain a highly conserved N-terminal motif termed the SCAN (named after SRE-ZBP, CTfin51, AW-1 and Number 18 cDNA) domain. The SCAN domain has been shown to be able to mediate homo- and hetero-oligomerisation [ (PUBMED:10567577) ]. These proteins can either activate or repress transcription, although isolated recombinant SCAN domains do not modulate significantly the transcription [ (PUBMED:8065901) (PUBMED:7673192) ]. In addition to these zinc finger transcription factors, an isolated SCAN domain without adjacent zinc finger motifs has been identified in some proteins [ (PUBMED:10393183) (PUBMED:10747874) ]. It has been noted that the SCAN domain resembles a domain-swapped version of the C-terminal domain of the HIV capsid protein [ (PUBMED:15629724) ].
The SCAN domain is enriched in hydrophobic and negatively charged residues with a L-X(6)-L motif at its core. This core is flanked by A, E, L, M, H and C residues that are frequently found in alpha-helices [ (PUBMED:7673192) ]. Predictions of the secondary structure of the domain suggest the presence of at least three alpha-helices that are separated from one another by short looped regions bounded by proline residues [ (PUBMED:10567577) ]. It has been shown to be a selective oligomerization domain that mediates homotypic and heterotypic interactions between SCAN box containing proteins [ (PUBMED:10747874) (PUBMED:10567577) ].
Family alignment:
There are 9360 SCAN domains in 9259 proteins in SMART's nrdb database.
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Evolution (species in which this domain is found)
Taxonomic distribution of proteins containing SCAN domain.
This tree includes only several representative species. The complete taxonomic breakdown of all proteins with SCAN domain is also avaliable.
Click on the protein counts, or double click on taxonomic names to display all proteins containing SCAN domain in the selected taxonomic class.
Literature (relevant references for this domain)
Primary literature is listed below; Automatically-derived, secondary literature is also avaliable.
Isolation and characterization of a novel zinc-finger protein with transcription repressor activity.
J Biol Chem. 1995; 270: 22143-52
Display abstract
To identify genes that can repress the expression of growth regulatory molecules, a human fetal cDNA library was screened with a degenerate oligonucleotide that corresponds to the conserved stretch of 6 amino acids connecting successive zinc-finger regions in the Wilms' tumor suppressor/Egr-1 family of DNA-binding proteins. One clone, designated zinc-finger protein 174 (ZNF174), corresponds to a putative transcription factor with three zinc fingers and a novel finger-associated domain, designated the SCAN box. The three Cys2-His2-type zinc fingers are positioned at the carboxyl terminus, while the 65-amino acid finger-associated SCAN box is located near the amino terminus. Chromosomal localization using somatic cell hybrid analysis and fluorescent in situ hybridization mapped the gene for ZNF174 to human chromosome 16p13.3. The 2.5-kilobase transcript from this gene is expressed in a variety of human organs, but most strongly in adult testis and ovary. Fusion of the upstream regulatory region of ZNF174 to the DNA-binding domain of GAL4 revealed that the gene could confer a repression function on the heterologous DNA-binding domain. ZNF174 selectively repressed reporter activity driven by the platelet-derived growth factor-B chain and transforming growth factor-beta 1 promoters and bound to DNA in a specific manner. This member of the C2H2-type zinc-finger family is a novel transcriptional repressor.
