LSM domain

The LSM domain contains Sm proteins as well as other related LSM (Like Sm) proteins. The U1, U2, U4/U6, and U5 small nuclear ribonucleoprotein particles (snRNPs) involved in pre-mRNA splicing contain seven Sm proteins (B/B', D1, D2, D3, E, F and G) in common, which assemble around the Sm site present in four of the major spliceosomal small nuclear RNAs. The U6 snRNP binds to the LSM (Like Sm) proteins [3]. Sm proteins are also found in archaebacteria, which do not have any splicing apparatus suggesting a more general role for Sm proteins. All Sm proteins contain a common sequence motif in two segments, Sm1 and Sm2, separated by a short variable linker. This family also includes the bacterial Hfq (host factor Q) proteins. Hfq are also RNA-binding proteins, that form hexameric rings.

Literature references

1. Hermann H, Fabrizio P, Raker VA, Foulaki K, Hornig H, Brahms H, Luhrmann R , EMBO J 1995;14:2076-2088.: snRNP Sm proteins share two evolutionarily conserved sequence motifs which are involved in Sm protein-protein interactions. PUBMED:7744013

2. Kambach C, Walke S, Young R, Avis JM, de la Fortelle E, Raker VA, Luhrmann R, Li J, Nagai K; , Cell 1999;96:375-387.: Crystal structures of two Sm protein complexes and their implications for the assembly of the spliceosomal snRNPs. PUBMED:10025403

3. Mayes AE, Verdone L, Legrain P, Beggs JD; , EMBO J 1999;18:4321-4331.: Characterization of Sm-like proteins in yeast and their association with U6 snRNA. PUBMED:10428970

4. Hajnsdorf E, Regnier P; , Proc Natl Acad Sci U S A 2000;97:1501-1505.: Host factor Hfq of Escherichia coli stimulates elongation of poly(A) tails by poly(A) polymerase I. PUBMED:10677490

5. Vytvytska O, Moll I, Kaberdin VR, von Gabain A, Blasi U; , Genes Dev 2000;14:1109-1118.: Hfq (HF1) stimulates ompA mRNA decay by interfering with ribosome binding. PUBMED:10809669

6. Kufel J, Allmang C, Petfalski E, Beggs J, Tollervey D; , J Biol Chem 2003;278:2147-2156.: Lsm Proteins are required for normal processing and stability of ribosomal RNAs. PUBMED:12438310

InterPro entry IPR001163

This family is found in Lsm (like-Sm) proteins and in bacterial Lsm-related Hfq proteins. In each case, the domain adopts a core structure consisting of an open beta-barrel with an SH3-like topology.

Lsm (like-Sm) proteins have diverse functions, and are thought to be important modulators of RNA biogenesis and function PUBMED:10801455, PUBMED:12438310. The Sm proteins form part of specific small nuclear ribonucleoproteins (snRNPs) that are involved in the processing of pre-mRNAs to mature mRNAs, and are a major component of the eukaryotic spliceosome. Most snRNPs consist of seven Sm proteins (B/B', D1, D2, D3, E, F and G) arranged in a ring on a uridine-rich sequence (Sm site), plus a small nuclear RNA (snRNA) (either U1, U2, U5 or U4/6) PUBMED:15130578. All Sm proteins contain a common sequence motif in two segments, Sm1 and Sm2, separated by a short variable linker PUBMED:7744013. In other snRNPs, certain Sm proteins are replaced with different Lsm proteins, such as with U7 snRNPs, in which the D1 and D2 Sm proteins are replaced with U7-specific Lsm10 and Lsm11 proteins, where Lsm11 plays a role in histone U7-specific RNA processing PUBMED:15526162. Lsm proteins are also found in archaebacteria, which do not have any splicing apparatus suggesting a more general role for Lsm proteins.

The pleiotropic translational regulator Hfq (host factor Q) is a bacterial Lsm-like protein, which modulates the structure of numerous RNA molecules by binding preferentially to A/U-rich sequences in RNA PUBMED:15561140. Hfq forms an Lsm-like fold, however, unlike the heptameric Sm proteins, Hfq forms a homo-hexameric ring.

External database links

Below is a listing of the unique domain organisations or architectures in which this domain is found. More...

There are various ways to view or download the sequence alignments that we store. You can use a sequence viewer to look at either the seed or full alignment for the family, or you can look at a plain text version of the sequence in a variety of different formats. More...

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Very large alignments can often cause problems for the formatting tool above. If you find that downloading or viewing a large alignment is problematic, you can also download a gzip-compressed, Stockholm-format file containing the seed or full alignment for this family.

You can also download a FASTA format file containing the full-length sequences for all sequences in the full alignment.

The main seed and full alignments are generated using sequences from the UniProt sequence database. However, we also generate alignments using sequences from the NCBI sequence database and the "metaseq" metagenomics dataset.

You can view alignments from these two additional datasets using the form above, or you can download alignments of NCBI or metagenomics sequences, as gzip-compressed files.

External links

MyHits provides a collection of tools to handle multiple sequence alignments. For example, one can refine a seed alignment (sequence addition or removal, re-alignment or manual edition) and then search databases for remote homologs using HMMER2.

HMM logos is one way of visualising profile HMMs. Logos provide a quick overview of the properties of an HMM in a graphical form. You can see a more detailed description of HMM logos and find out how you can interpret them here. More...

This page displays the phylogenetic tree for this family. We use FastTree to calculate neighbour join trees with a local bootstrap based on 100 resamples (shown next to the tree nodes). FastTree calculates approximately-maximum-likelihood phylogenetic trees from our seed or full alignments.

Note: You can also download the data files for the seed, full, NCBI or metagenomics trees.

This section shows the detailed information about the Pfam family. You can see the definitions of many of the terms in this section in the glossary and a fuller explanation of the scoring system that we use in the scores section of the help pages.

Curation

HMM information

There is 1 interaction for this family. More...

For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the MSD 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 LSM domain has been found.