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Search results 1 to 34 out of 34 for Myb

Category restricted to ProteinDomain (x)

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Categories

Category: ProteinDomain
Type Details Score
Protein Domain
Type: Domain
Description: The myb-type HTH domain is a DNA-binding, helix-turn-helix (HTH) domain of approximately 55 amino acids, typically occurring in a tandem repeat in eukaryotic transcription factors. The domain is named after the retroviral oncogene v-myb, and its cellular counterpart c-myb, which encode nuclear DNA-binding proteins that specifically recognise the sequence YAAC(G/T)G [, ]. Myb proteins contain three tandem repeats of 51 to 53 amino acids, termed R1, R2 and R3. This repeat region is involved in DNA-binding and R2 and R3 bind directly to the DNA major groove. The major part of the first repeat is missing in retroviral v-Myb sequences and in plant myb-related (R2R3) proteins []. A single myb-type HTH DNA-binding domain occurs in TRF1 and TRF2.The 3D-structure of the myb-type HTH domain forms three α-helices []. The second and third helices connected via a turn comprisethe helix-turn-helix motif. Helix 3 is termed the recognition helix as itbinds the DNA major groove, like in other HTHs.
Protein Domain
Type: Family
Description: This entry includes single myb histone 1-6 (SMH1-6) from maize and telomere repeat-binding factor 1-5 (TRB1-5) from Arabidopsis. They are a group of proteins that bind telomere DNA repeats [, ]. This entry also includes uncharacterised proteins from fungi.
Protein Domain
Type: Domain
Description: Rap1 Myb adopts a canonical three-helix bundle tertiary structure, with the second and third helices forming a helix-turn-helix variant motif. The function is unclear but it may either interact with DNA via an adaptor protein or it may be only involved in protein-protein interactions [].
Protein Domain
Type: Family
Description: L10-interacting MYB domain-containing protein (LIMYB) is a transcriptional repressor that associates with ribosomal protein promoters []. It interacts with NIK1, a leucine-rich repeat receptor-like kinase (LRR-RLK), the virulence target of the begomovirus nuclear shuttle protein, leading to global translation suppression as an antiviral immunity strategy in plants [].
Protein Domain
Type: Family
Description: This entry represents a group of plant Myb family transcription factors, including HHO1-6, HRS1 and EFM from Arabidopsis. HRS1 represses primary root development in response to phosphate deficiency conditions, only when nitrate is present []. It is also required for suppressing abscisic acid (ABA) signalling in germinating embryo axis, which promotes the timely germination of seeds []. EFM functions as a flowering repressor, directly repressing FT expression in a dosage-dependent manner in the leaf vasculature [].
Protein Domain
Type: Domain
Description: This DNA-binding domain is restricted to (but common in) plant proteins, many of which also contain a response regulator domain. The domain appears related to the Myb-like DNA-binding domain [, ].
Protein Domain
Type: Family
Description: Tom1 (target of Myb 1) and its related proteins (Tom1L1 and Tom1L2) constitute a protein family and share an N-terminal VHS (Vps27p/Hrs/Stam) domain followed by a GAT (GGA and Tom1) domain.VHS domains are found at the N termini of select proteins involved in intracellular membrane trafficking and are often localized to membranes. The three dimensional structure of human TOM1 VHS domain reveals eight helices arranged in a superhelix. The surface of the domain has two main features: (1) a basic patch on one side due to several conserved positively charged residues on helix 3 and (2) a negatively charged ridge on the opposite side, formed by residues on helix 2 []. The basic patch is thought to mediate membrane binding.It was demonstrated that the GAT domain of both Tom1 and Tom1L1 binds ubiquitin, suggesting that these proteins might participate in the sorting of ubiquitinated proteins into multivesicular bodies (MVB) []. Moreover, Tom1L1 interacts with members of the MVB sorting machinery. Specifically, the VHS domain of Tom1L1 interacts with Hrs (hepatocyte growth factor-regulated tyrosine kinase substrate), whereas a PTAP motif, located between the VHS and GAT domains of Tom1L1, is responsible for binding to TSG101 (tumour susceptibility gene 101). Myc epitope-tagged Tom1L1 is recruited to endosomes following Hrs expression. In addition, Tom1L1 possesses several tyrosine motifs at the C-terminal region that mediate interactions with members of the Src family kinases and other signalling proteins such as Grb2 and p85. Expression of a constitutively active form of Fyn kinase promotes the recruitment of Tom1L1 to enlarged endosomes. It is proposed that Tom1L1 could act as an intermediary between the signalling and degradative pathways [].Over expression of Tom1 suppresses activation of the transcription factors NF-kappaB and AP-1, induced by either IL-1beta or tumour necrosis factor (TNF)-alpha, and the VHS domain of Tom1 is indispensable for this suppressive activity. This suggests that Tom1 is a common negative regulator of signalling pathways induced by IL-1beta and TNF-alpha [].
Protein Domain
Type: Domain
Description: This entry represents the Myb domain found in transcription factor TFIIIB component B''.Transcription by RNA polymerase III (pol III) is a complex molecular process orchestrated by the two main transcription factors, TFIIIB and TFIIIC. The TFIIIB complex can be recruited by TFIIIC to upstream DNA and form an exceptionally kinetically stable TFIIIB-DNA complex, which then recruits the Pol III enzymatic complex and helps maintain it for multiple transcription cycles in a process called facilitated recycling []. Saccharomyces cerevisiae TFIIIB is a complex of three subunits, the TATA box-binding protein TBP, the TFIIB-related factor BRF, and the beta'' protein. The myb-type HTH domain is a DNA-binding, helix-turn-helix (HTH) domain of approximately 55 amino acids, typically occurring in a tandem repeat in eukaryotic transcription factors. The domain is named after the retroviral oncogene v-myb, and its cellular counterpart c-myb, which encode nuclear DNA-binding proteins that specifically recognise the sequence YAAC(G/T)G [, ].
Protein Domain
Type: Domain
Description: This is the N-terminal region of a family of MYB and MYC transcription factors. The DNA-binding HLH domain is further downstream, . Members of the MYB and MYC family regulate the biosynthesis of phenylpropanoids in several plant species [, ].
Protein Domain
Type: Family
Description: This entry includes Caenorhabditis elegans Knl2 (kinetochore null protein 2) and related proteins. Knl2 is a Myb DNA-binding domain-containing protein required for CENP-A loading and kinetochore assembly [].
Protein Domain
Type: Family
Description: This entry represents a group of plant MYB transcription factors, including RADIALIS and RADIALIS-like 1-6. RADIALIS is specifically expressed in the dorsal region of developing flowers and is involved in the dorsoventral asymmetry of flowers [].
Protein Domain
Type: Homologous_superfamily
Description: This superfamily represents the Myb-like DNA-binding domain of Knl2 (kinetochore null protein 2) from C. elegans, a Myb DNA-binding domain-containing protein required for CENP-A loading and kinetochore assembly []. It has an all-helical structure.
Protein Domain
Type: Domain
Description: This entry represents the C-terminal domain of the RTC4 (restriction of telomere capping protein 4) protein from yeasts. In Saccharomyces cerevisiae, deletion of RTC4 affects the cell response to telomere uncapping []. This domain is also found in proteins that contain a DNA-binding myb domain.
Protein Domain
Type: Family
Description: This entry represents LIN-9-related proteins from plants (also known as proteins ALWAYS EARLY). In Arabidopsis thaliana, there are three ALWAYS EARLY homologues (AtALY1, AtALY2 and AtALY3). Unlike animal ALY/LIN-9 proteins, AtALY1 contains an additional N-terminal myb domain and a TUDOR related domain in part of the ALY/LIN-9 conserved domain [].
Protein Domain
Type: Domain
Description: This domain, found in L10-interacting MYB domain-containing protein (LIMYB) and At2g29880 from Arabidopsis, is related to Myb/SANT-like DNA binding domains. LIMYB is a transcription factor that associates with ribosomal protein promoters. It is involved in global translation suppression as an antiviral immunity strategy in plants [].
Protein Domain
Type: Family
Description: TMX2 contain the TRX domain, an N-terminal signal peptide, a potential transmembrane domain, an Myb DNA-binding domain repeat signature, an endoplasmic reticulum (ER) membrane retention signal (KKXX-like motif), and a dileucine motif in the tail. In TMX2, the TRX domain redox active CXXC motif is replaced with SXXC [, ]. Its function is not clear. Homologues are found only in metazoa.
Protein Domain
Type: Domain
Description: This domain, approximately 90 residues, is mainly found in DNA methyltransferase 1-associated protein 1 (DAMP1), which plays an important role in development and maintenance of genome integrity in various mammalian species [, ]. It mainly consists of tandem repeats of three α-helices that are arranged in a helix-turn-helix motif and shows a structural similarity with SANT domain and Myb DNA-binding domain, indicating it contains a putative DNA-binding site [].
Protein Domain
Type: Family
Description: This entry represents a group of plant Myb domain proteins, including LUX, BOA and MYBC1 from Arabidopsis. LUX and BOA are transcription factors and critical components of the regulatory circuit of the circadian clock [, ]. LUX also binds toELF3 and associates with ELF4 in a diurnal complex which is required for the expression of the growth-promoting transcription factors PIF4 and PIF5 and subsequent hypocotyl growth in the early evening []. MYBC1 has been shown to negatively regulate freezing tolerance in Arabidopsis [].
Protein Domain
Type: Domain
Description: This domain adopts a secondary structure consisting of a pair of long, antiparallel α-helices (thestem) that support a three-helix bundle (3HB) at their end. The 3HB contains a helix-turn-helix motif and is similar to the DNA binding domains of the bacterial site-specific recombinases, and of eukaryotic Myb and homeodomain transcription factors. The Tower domain has an important role in the tumour suppressor function of BRCA2, and is essential for appropriate binding of BRCA2 to DNA [].
Protein Domain
Type: Domain
Description: This entry represents the thioredoxin (TRX) domain found in thioredoxin-related transmembrane protein 2 (TMX2). In TMX2, the TRX domain redox active CXXC motif is replaced with SXXC. In addition to the TRX domain, TMX2 may contain an N-terminal signal peptide, a potential transmembrane domain, an Myb DNA-binding domain repeat signature, an endoplasmic reticulum (ER) membrane retention signal (KKXX-like motif), and a dileucine motif in the tail [, ].
Protein Domain
Type: Family
Description: This entry represents a group of Myb transcription factors from plants, including protein rough sheath 2 (RS2) and ASSYMMETRIC LEAVES1 (Asn1) [, ]. They repress Knotted1-type homeobox (KNOX) genes and are required to establish determinacy during leaf development. RS2/AS1 interacts with the DNA binding factor ASYMMETRIC LEAVES2, a predicted RNA binding protein (RIK, for RS2-Interacting KH protein), and a homologue of the chromatin-remodeling protein HIRA. Together with HIRA, RS2/AS1 mediates the epigenetic silencing of knox genes, possibly by modulating chromatin structure [].
Protein Domain
Type: Family
Description: This entry represents a group of KH domain containing proteins from eukaryotes, including RIK (rough sheath 2-interacting KH domain) from plants and BLOM7 (also known as KH homology domain-containing protein 4) from animals. RIK1 interacts with rough sheath2 (RS2), which is a myb domain protein required to repress knox genes during leaf development []. BLOM7 is a RNA-binding protein involved in pre-mRNA splicing []. It has been shown to interact with SNEV (Prp19/Pso4), a splicing factor [].
Protein Domain
Type: Domain
Description: The SWIRM domain is a small α-helical domain of about 85 amino acid residues found in eukaryotic chromosomal proteins. It is named after the proteins SWI3, RSC8 and MOIRA in which it was first recognised. This domain mediates protein-protein interactions in the assembly of chromatin-protein complexes [, ]. The yeast SWI3 SWIRM structure revealed that it forms a four-helix globular domain containing a helix-turn-helix motif [].The SWIRM domain can be linked to different domains, such as the ZZ-type zinc finger (), the Myb DNA-binding domain (), the HORMA domain (), the amino-oxidase domain, the chromo domain (), and the JAB1/PAD1 domain.
Protein Domain
Type: Family
Description: The LNK family consists of light and clock regulated morning genes from plants. These control both the pace of circadian rhythms and the photoperiodic regulation of flowering time by promoting the expression of a subset of clock and flowering time genes in the afternoon []. The LCL domain of clock-related factor REVEILLE8 recruits LNKs to target promoters, while its MYB domain provides DNA binding specificity. In turn, LNKs interact with RNA Polymerase II and the transcript elongation FACT complex, resulting in rhythmic changes of gene expression [].
Protein Domain
Type: Domain
Description: The retroviral oncogene v-myb, and its cellular counterpart c-myb, encode nuclear DNA-binding proteins. In myb, one of the most conserved regions consisting of three tandem repeats has been shown to be involved in DNA-binding [].The SANT domain is present in nuclear receptor co-repressors and in the subunits of many chromatin-remodelling complexes []. It has a strong structural similarity to the DNA-binding domain of Myb-related proteins []. Both consist of tandem repeats of three α-helices that are arranged in a helix-turn-helix motif, each alpha helix containing a bulky aromatic residue. Despite the overall similarity there are differences that indicate that the SANT domain is functionally divergent from the canonical Myb DNA-binding domain [].The myb/SANT domains can be classified into three groups: the myb-type HTH domain, which binds DNA, the SANT domain, which is a protein-protein interaction module, and the myb-like domain that can be involved in either of these functions. This entry represents a myb-like domain.
Protein Domain
Type: Family
Description: This entry represents a group of plant MYB-like transcription factors, including EOBI and EOBII from Petunia hybrida. EOBII controls the production of volatile organic compounds (VOCs), including floral volatile benzenoids and phenylpropanoids (FVBP), in flowers of fragrant cultivars (e.g. cv. Mitchell and cv. V26) by regulating the expression of ODO1 and EOBI, key regulators of the shikimate pathway, and of several biosynthetic floral scent-related genes including IGS, PAL2 and CFAT [, , ]. EOBII binds to and activates the ODO1 and EOBI promoters via MYB binding sites (MBS) 5'-AAACCTAAT-3' and 5'-CTAACT-3' [, , , ].Other MYB-like transcription factors included in this entry include MYB21/MYB24/MYB108 from Arabidopsis [, ]and MYB2/JAMYB from rice [, ]. They are involved in different processes, such as abiotic stress responses, defense responses, plant development and photomorphogenesis.
Protein Domain
Type: Domain
Description: The MADF (myb/SANT-like domain in Adf-1) domain is an approximately 80-amino-acid module that directs sequence specific DNA binding to a site consisting of multiple tri-nucleotide repeats. The MADF domain is found in one or more copies in eukaryotic and viral proteins and is often associated with the BESS domain []. MADF is related to the Myb DNA-binding domain (). The retroviral oncogene v-myb, and its cellular counterpart c-myb, are nuclear DNA-binding proteins that specifically recognise the sequence YAAC(G/T)G. It is likely that the MADF domain is more closely related to the myb/SANT domain than it is to other HTH domains. Some proteins known to contain a MADF domain are listed below: Drosophila Adf-1, a transcription factor first identified on the basis of its interaction with the alcohol dehydrogenase promoter but that binds the promoters of a diverse group of genes []. Drosophila Dorsal-interacting protein 3 (Dip3), which functions both as an activator to bind DNA in a sequence specific manner and a coactivator to stimulate synergistic activation by Dorsal and Twist []. Drosophila Stonewall (Stwl), a putative transcription factor required for maintenance of female germline stem cells as well as oocyte differentiation.
Protein Domain
Type: Homologous_superfamily
Description: Telomeres function to shield chromosome ends from degradation and end-to-end fusions, as well as preventing the activation of DNA damage checkpoints. Telomeric repeat binding factor (TRF) proteins TRF1 and TRF2 are major components of vertebrate telomeres required for regulation of telomere stability. TRF1 and TRF2 bind to telomeric DNA as homodimers. Dimerisation involves the TRF homology (TRFH) subdomain contained within the dimerisation domain. The TRFH subdomain is important not only for dimerisation, but for DNA binding, telomere localisation, and interactions with other telomeric proteins. The dimerisation domains of TRF1 and TRF2 show the same multi-helical structure, arranged in a solenoid conformation similar to TPR repeats, which can be divided into an α-α superhelix and a long alpha hairpin [].The two related human TRF proteins hTRF1 and hTRF2 form homodimers and bind directly to telomeric TTAGGG repeats via the myb DNA binding domain at the carboxy terminus []. TRF1 is implicated in telomere length regulation and TRF2 in telomere protection []. Other telomere complex associated proteins are recruited through their interaction with either TRF1 or TRF2. The fission yeast protein Taz1p (telomere-associated in Schizosaccharomyces pombe (Fission yeast) has similarity to both hTRF1 and hTRF2 and may perform the dual functions of TRF1 and TRF2 at fission yeast telomeres []. This entry represents the dimerisation domain.
Protein Domain
Type: Homologous_superfamily
Description: Homeobox domain (also known as homeodomain) proteins are transcription factors that share a related DNA binding homeodomain []. The homeodomain was first identified in a number of Drosophila homeotic and segmentation proteins, but is now known to be well conserved in many other animals, including vertebrates. The domain binds DNA through a helix-turn-helix (HTH) structure. The HTH motif is characterised by two α-helices, which make intimate contacts with the DNA and are joined by a short turn. The second helix binds to DNA via a number of hydrogen bonds and hydrophobic interactions, which occur between specific side chains and the exposed bases and thymine methyl groups within the major groove of the DNA. The first helix helps to stabilise the structure. Many proteins contain homeodomains, including Drosophila Engrailed, yeast mating type proteins, hepatocyte nuclear factor 1a and HOX proteins.The homeodomain motif is very similar in sequence and structure to domains in a wide range of DNA-binding proteins, including recombinases, Myb proteins, GARP response regulators, human telomeric proteins (hTRF1), paired domain proteins (PAX), yeast RAP1, centromere-binding proteins CENP-B and ABP-1, transcriptional regulators (TyrR), AraC-type transcriptional activators, and tetracycline repressor-like proteins (TetR, QacR, YcdC) [, , ].
Protein Domain
Type: Family
Description: This group represents telomeric repeat-binding factors 1 (TERF1, also known as TRF1).Telomeres function to shield chromosome ends from degradation and end-to-end fusions, as well as preventing the activation of DNA damage checkpoints. Telomeric repeat binding factor (TRF) proteins TRF1 and TRF2 are major components of vertebrate telomeres required for regulation of telomere stability. TRF1 and TRF2 bind to telomeric DNA as homodimers. Dimerisation involves the TRF homology (TRFH) subdomain contained within the dimerisation domain. The TRFH subdomain is important not only for dimerisation, but for DNA binding, telomere localisation, and interactions with other telomeric proteins. The dimerisation domains of TRF1 and TRF2 show the same multi-helical structure, arranged in a solenoid conformation similar to TPR repeats, which can be divided into an α-α superhelix and a long alpha hairpin [].The two related human TRF proteins hTRF1 and hTRF2 form homodimers and bind directly to telomeric TTAGGG repeats via the myb DNA binding domain at the carboxy terminus []. TRF1 is implicated in telomere length regulation and TRF2 in telomere protection []. Other telomere complex associated proteins are recruited through their interaction with either TRF1 or TRF2. The fission yeast protein Taz1p (telomere-associated in Schizosaccharomyces pombe (Fission yeast) has similarity to both hTRF1 and hTRF2 and may perform the dual functions of TRF1 and TRF2 at fission yeast telomeres [].
Protein Domain
Type: Family
Description: This entry represents telomeric repeat-binding factor 2 (TERF2, also known as TRF2).Telomeres function to shield chromosome ends from degradation and end-to-end fusions, as well as preventing the activation of DNA damage checkpoints. Telomeric repeat binding factor (TRF) proteins TRF1 and TRF2 are major components of vertebrate telomeres required for regulation of telomere stability. TRF1 and TRF2 bind to telomeric DNA as homodimers. Dimerisation involves the TRF homology (TRFH) subdomain contained within the dimerisation domain. The TRFH subdomain is important not only for dimerisation, but for DNA binding, telomere localisation, and interactions with other telomeric proteins. The dimerisation domains of TRF1 and TRF2 show the same multi-helical structure, arranged in a solenoid conformation similar to TPR repeats, which can be divided into an α-α superhelix and a long alpha hairpin [].The two related human TRF proteins hTRF1 and hTRF2 form homodimers and bind directly to telomeric TTAGGG repeats via the myb DNA binding domain at the carboxy terminus []. TRF1 is implicated in telomere length regulation and TRF2 in telomere protection []. Other telomere complex associated proteins are recruited through their interaction with either TRF1 or TRF2. The fission yeast protein Taz1p (telomere-associated in Schizosaccharomyces pombe (Fission yeast) has similarity to both hTRF1 and hTRF2 and may perform the dual functions of TRF1 and TRF2 at fission yeast telomeres [].
Protein Domain
Type: Domain
Description: Telomeres function to shield chromosome ends from degradation and end-to-end fusions, as well as preventing the activation of DNA damage checkpoints. Telomeric repeat binding factor (TRF) proteins TRF1 and TRF2 are major components of vertebrate telomeres required for regulation of telomere stability. TRF1 and TRF2 bind to telomeric DNA as homodimers. Dimerisation involves the TRF homology (TRFH) subdomain contained within the dimerisation domain. The TRFH subdomain is important not only for dimerisation, but for DNA binding, telomere localisation, and interactions with other telomeric proteins. The dimerisation domains of TRF1 and TRF2 show the same multi-helical structure, arranged in a solenoid conformation similar to TPR repeats, which can be divided into an α-α superhelix and a long alpha hairpin [].The two related human TRF proteins hTRF1 and hTRF2 form homodimers and bind directly to telomeric TTAGGG repeats via the myb DNA binding domain at the carboxy terminus []. TRF1 is implicated in telomere length regulation and TRF2 in telomere protection []. Other telomere complex associated proteins are recruited through their interaction with either TRF1 or TRF2. The fission yeast protein Taz1p (telomere-associated in Schizosaccharomyces pombe (Fission yeast) has similarity to both hTRF1 and hTRF2 and may perform the dual functions of TRF1 and TRF2 at fission yeast telomeres []. This entry represents the dimerisation domain.
Protein Domain
Type: Homologous_superfamily
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. Pirh2 is an eukaryotic ubiquitin protein ligase, which has been shown to promote p53 degradation in mammals. Pirh2 physically interacts with p53 and promotes ubiquitination of p53 independently of MDM2. Like MDM2, Pirh2 is thought to participate in an autoregulatory feedback loop that controls p53 function. Pirh2 proteins contain three distinct zinc fingers, the CHY-type, the CTCHY-type which is C-terminal to the CHY-type zinc finger and a RING finger. The CHY-type zinc finger has no currently known function [].As well as Pirh2, the CHY-type zinc finger is also found in the following proteins:Yeast helper of Tim protein 13. Hot13 may have a role in the assembly and recycling of the small Tims, a complex of the mitochondrial intermembrane space that participates in the TIM22 import pathway for assembly of the inner membrane []Several plant hypothetical proteins that also contain haemerythrin cation binding domainsSeveral protozoan hypothetical proteins that also contain a Myb domainThe solution structure of this zinc finger has been solved and binds three zinc atoms as shown in the following schematic representation:++---------+-----+|| | |CXHYxxxxxxxxxCCxxxxxCxxCHxxxxxHxxxxxxxxxxxCxxCxxxxxxxxxCxxC| | | | | | | |+-+-----------------+--+ +--+---------+--+'C': conserved cysteine involved in the binding of one zinc atom.'H': conserved histidine involved in the binding of one zinc atom.
Protein Domain
Type: Domain
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. Pirh2 is an eukaryotic ubiquitin protein ligase, which has been shown to promote p53 degradation in mammals. Pirh2 physically interacts with p53 and promotes ubiquitination of p53 independently of MDM2. Like MDM2, Pirh2 is thought to participate in an autoregulatory feedback loop that controls p53 function. Pirh2 proteins contain three distinct zinc fingers, the CHY-type, the CTCHY-type which is C-terminal to the CHY-type zinc finger and a RING finger. The CHY-type zinc finger has no currently known function [].As well as Pirh2, the CHY-type zinc finger is also found in the following proteins:Yeast helper of Tim protein 13. Hot13 may have a role in the assembly and recycling of the small Tims, a complex of the mitochondrial intermembrane space that participates in the TIM22 import pathway for assembly of the inner membrane []Several plant hypothetical proteins that also contain haemerythrin cation binding domainsSeveral protozoan hypothetical proteins that also contain a Myb domainThe solution structure of this zinc finger has been solved and binds three zinc atoms as shown in the following schematic representation:++---------+-----+|| | |CXHYxxxxxxxxxCCxxxxxCxxCHxxxxxHxxxxxxxxxxxCxxCxxxxxxxxxCxxC| | | | | | | |+-+-----------------+--+ +--+---------+--+'C': conserved cysteine involved in the binding of one zinc atom.'H': conserved histidine involved in the binding of one zinc atom.