Summary: U1 zinc finger
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This family consists of several U1 small nuclear ribonucleoprotein C (U1-C) proteins. The U1 small nuclear ribonucleoprotein (U1 snRNP) binds to the pre-mRNA 5' splice site (ss) at early stages of spliceosome assembly. Recruitment of U1 to a class of weak 5' ss is promoted by binding of the protein TIA-1 to uridine-rich sequences immediately downstream from the 5' ss. Binding of TIA-1 in the vicinity of a 5' ss helps to stabilise U1 snRNP recruitment, at least in part, via a direct interaction with U1-C, thus providing one molecular mechanism for the function of this splicing regulator . This domain is probably a zinc-binding. It is found in multiple copies in some members of the family.
Forch P, Puig O, Martinez C, Seraphin B, Valcarcel J; , EMBO J 2002;21:6882-6892.: The splicing regulator TIA-1 interacts with U1-C to promote U1 snRNP recruitment to 5' splice sites. PUBMED:12486009 EPMC:12486009
External database links
This tab holds annotation information from the InterPro database.
InterPro entry IPR013085
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 [PUBMED:10529348, PUBMED:15963892, PUBMED:15718139, PUBMED:17210253, PUBMED:12665246]. 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 [PUBMED:11179890]. Zinc-binding motifs are stable structures, and they rarely undergo conformational changes upon binding their target.
C2H2-type (classical) zinc fingers (Znf) were the first class to be characterised. They contain a short beta hairpin and an alpha helix (beta/beta/alpha structure), where a single zinc atom is held in place by Cys(2)His(2) (C2H2) residues in a tetrahedral array. C2H2 Znf's can be divided into three groups based on the number and pattern of fingers: triple-C2H2 (binds single ligand), multiple-adjacent-C2H2 (binds multiple ligands), and separated paired-C2H2 [PUBMED:11361095]. C2H2 Znf's are the most common DNA-binding motifs found in eukaryotic transcription factors, and have also been identified in prokaryotes [PUBMED:10664601]. Transcription factors usually contain several Znf's (each with a conserved beta/beta/alpha structure) capable of making multiple contacts along the DNA, where the C2H2 Znf motifs recognise DNA sequences by binding to the major groove of DNA via a short alpha-helix in the Znf, the Znf spanning 3-4 bases of the DNA [PUBMED:10940247]. C2H2 Znf's can also bind to RNA and protein targets [PUBMED:18253864].
This entry represents a C2H2-type zinc finger motif found in several U1 small nuclear ribonucleoprotein C (U1-C) proteins. Some proteins contain multiple copies of this motif. The U1 small nuclear ribonucleoprotein (U1 snRNP) binds to the pre-mRNA 5' splice site at early stages of spliceosome assembly. Recruitment of U1 to a class of weak 5' splice site is promoted by binding of the protein TIA-1 to uridine-rich sequences immediately downstream from the 5' splice site. Binding of TIA-1 in the vicinity of a 5' splice site helps to stabilise U1 snRNP recruitment, at least in part, via a direct interaction with U1-C, thus providing one molecular mechanism for the function of this splicing regulator [PUBMED:12486009].
More information about these proteins can be found at Protein of the Month: Zinc Fingers [PUBMED:].
|Molecular function||zinc ion binding (GO:0008270)|
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Superfamily of classical and closely related C2H2 or beta-beta-alpha zinc finger DNA-binding domains.
The clan contains the following 19 members:4F5 DUF3449 GAGA Sgf11 zf-AD zf-BED zf-C2H2 zf-C2H2_2 zf-C2H2_4 zf-C2H2_6 zf-C2H2_7 zf-C2H2_jaz zf-C2HC_2 zf-Di19 zf-H2C2_2 zf-H2C2_5 zf-met zf-met2 zf-U1
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Curation and family details
|Seed source:||Pfam-B_10606 (release 9.0)|
|Previous IDs:||zf-U1; U1_C;|
|Number in seed:||11|
|Number in full:||661|
|Average length of the domain:||36.70 aa|
|Average identity of full alignment:||41 %|
|Average coverage of the sequence by the domain:||15.13 %|
|HMM build commands:||
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 23193494 -E 1000 --cpu 4 HMM pfamseq
|Family (HMM) version:||7|
|Download:||download the raw HMM for this family|
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For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the PDBe group, to allow us to map Pfam domains onto UniProt sequences and three-dimensional protein structures. The table below shows the structures on which the zf-U1 domain has been found. There are 1 instances of this domain found in the PDB. Note that there may be multiple copies of the domain in a single PDB structure, since many structures contain multiple copies of the same protein seqence.
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