Summary: Smg-4/UPF3 family
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Smg-4/UPF3 family Provide feedback
This family contains proteins that are involved in nonsense mediated mRNA decay. A process that is triggered by premature stop codons in mRNA. The family includes Smg-4  and UPF3.
External database links
This tab holds annotation information from the InterPro database.
InterPro entry IPR005120
Nonsense-mediated mRNA decay (NMD) is a surveillance mechanism by which eukaryotic cells detect and degrade transcripts containing premature termination codons. Three 'up-frameshift' proteins, UPF1, UPF2 and UPF3, are essential for this process in organisms ranging from yeast, human to plants [PUBMED:11368911]. Exon junction complexes (EJCs) are deposited ~24 nucleotides upstream of exon-exon junctions after splicing. Translation causes displacement of the EJCs, however, premature translation termination upstream of one or more EJCs triggers the recruitment of UPF1, UPF2 and UPF3 and activates the NMD pathway [PUBMED:12718880, PUBMED:15048104].
This family contains UPF3. The crystal structure of the complex between human UPF2 and UPF3b, which are, respectively, a MIF4G (middle portion of eIF4G) domain and an RNP domain (ribonucleoprotein-type RNA-binding domain) has been determined to 1.95A. The protein-protein interface is mediated by highly conserved charged residues in UPF2 and UPF3b and involves the beta-sheet surface of the UPF3b ribonucleoprotein (RNP) domain, which is generally used by these domains to bind nucleic acids. In UPF3b the RNP domain does not bind RNA, whereas the UPF2 construct and the complex do. It is clear that some RNP domains have evolved for specific protein-protein interactions rather than as nucleic acid binding modules [PUBMED:15004547].
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This clan contains families that are related to the RNA recognition motif domains. However, not all these families are RNA binding.
The clan contains the following 15 members:BRAP2 Calcipressin DUF1866 Limkain-b1 Nup35_RRM Nup35_RRM_2 Ribosomal_L23 RNA_bind RRM_1 RRM_2 RRM_3 RRM_5 RRM_6 Smg4_UPF3 XS
We make a range of alignments for each Pfam-A family:
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Curation and family details
|Seed source:||Bateman A|
|Number in seed:||6|
|Number in full:||408|
|Average length of the domain:||159.80 aa|
|Average identity of full alignment:||33 %|
|Average coverage of the sequence by the domain:||36.82 %|
|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:||10|
|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 Smg4_UPF3 domain has been found. There are 3 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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