U6 snRNA-associated Sm-like protein LSm8 (LSM8)

The protein contains 96 amino acids for an estimated molecular weight of 10403 Da.

 

Plays role in pre-mRNA splicing as component of the U4/U6-U5 tri-snRNP complex that is involved in spliceosome assembly, and as component of the precatalytic spliceosome (spliceosome B complex) (PubMed:28781166). The heptameric LSM2-8 complex binds specifically to the 3'-terminal U-tract of U6 snRNA (PubMed:10523320). (updated: Nov. 7, 2018)

Protein identification was indicated in the following studies:

  1. Goodman and co-workers. (2013) The proteomics and interactomics of human erythrocytes. Exp Biol Med (Maywood) 238(5), 509-518.
  2. Lange and co-workers. (2014) Annotating N termini for the human proteome project: N termini and Nα-acetylation status differentiate stable cleaved protein species from degradation remnants in the human erythrocyte proteome. J Proteome Res. 13(4), 2028-2044.
  3. Hegedűs and co-workers. (2015) Inconsistencies in the red blood cell membrane proteome analysis: generation of a database for research and diagnostic applications. Database (Oxford) 1-8.

Methods

The following articles were analysed to gather the proteome content of erythrocytes.

The gene or protein list provided in the studies were processed using the ID mapping API of Uniprot in September 2018. The number of proteins identified and mapped without ambiguity in these studies is indicated below.
Only Swiss-Prot entries (reviewed) were considered for protein evidence assignation.

PublicationIdentification 1Uniprot mapping 2Not mapped /
Obsolete
TrEMBLSwiss-Prot
Goodman (2013)2289 (gene list)227853205992269
Lange (2014)123412347281224
Hegedus (2015)2638262202352387
Wilson (2016)165815281702911068
d'Alessandro (2017)18261817201815
Bryk (2017)20902060101081942
Chu (2018)18531804553621387

1 as available in the article and/or in supplementary material
2 uniprot mapping returns all protein isoforms as one entry

The compilation of older studies can be retrieved from the Red Blood Cell Collection database.

The data and differentiation stages presented below come from the proteomic study and analysis performed by our partners of the GReX consortium, more details are available in their published work.

No sequence conservation computed yet.

Interpro domains
Total structural coverage: 100%
Model score: 31

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The reference OMIM entry for this protein is 607288

Lsm8 protein; lsm8

DESCRIPTION

Sm-like proteins were identified in a variety of organisms based on sequence homology with the Sm protein family (see SNRPD2; 601061). Sm-like proteins contain the Sm sequence motif, which consists of 2 regions separated by a linker of variable length that folds as a loop. The Sm-like proteins are thought to form a stable heteromer present in tri-snRNP particles, which are important for pre-mRNA splicing.

CLONING

In a search for human Sm-like proteins, Achsel et al. (1999) fractionated proteins present in purified (U4/U6.U5) tri-snRNPs and isolated 7 Sm-like proteins, which they named LSm2-LSm8. Using partial peptide sequence for database searches, they identified and sequenced EST clones. Using additional sequence obtained by PCR amplification of a HeLa cDNA library, they assembled full-length cDNA sequences for LSM2-LSM8. Salgado-Garrido et al. (1999) searched database sequence for Sm proteins and identified 16 potential Sm-related genes in yeast as well as some Sm-related genes in human and archaebacteria. Using a multiple sequence alignment of Sm domains, they built a phylogenetic tree of yeast, human, and archaeal Sm and Sm-like proteins.

GENE FUNCTION

Using electron-microscopy, Achsel et al. (1999) observed that purified LSm proteins form a heteromer that is stable even in the absence of RNA and exhibits a doughnut-shaped structure similar to the Sm core RNP structure. They demonstrated that the purified LSm heteromer binds specifically to the U6 snRNA at its 3-prime-terminal U-tract. They also showed that the LSm proteins facilitate the formation of U4/U6 RNA duplexes in vitro and concluded that the LSm proteins may play a role in U4/U6 snRNP formation. Using immunoprecipitation experiments, Salgado-Garrido et al. (1999) concluded that there is a complex of 7 Sm-like proteins bound to RNA in yeast. Lsm2-Lsm8 coprecipitate the U4, U5 and U6 snRNAs and directly associate with the U6 snRNA present in the free U6 snRNP. Additionally, the yeast Lsm2-Lsm7 proteins were found to be associated with the pre-RNase P RNA but not the mature RNase RNA. Using immunoprecipitation experiments from human cell extracts, Salgado-Garrido et al. (1999) showed that the LSM3 and LSM4 proteins are specifically associated with snRNP complexes containing the U6 snRNA. Salgado-Garrido et al. (1999) concluded that Sm and Sm-like proteins assemble in at least 2 functionally conserved complexes of deep evolutionary origin. By disrupting the Sm and Sm-like genes in yeast, Salgado-Garrido et al. (1999) concluded that disruption of genes encoding Sm-like proteins directly associated with the U6 snRNA (Lsm2-8) generated variable phenotypes. Lsm2, Lsm3, Lsm4, and Lsm8 are essential for vegetative growth. Lsm5, Lsm6, and Lsm7 are not essential for growth; however, their disruptions lead to slow growth especially at elevated temperature. The levels of the U6 snRNA were strongly reduced in the strains harboring the Lsm5, Lsm6, and Lsm7 disruptions. Lsm1 and Lsm9 are dispensable for vegetative growth, but Lsm1 is required for optimal vegetative growth at 30 degrees and is temperature sensitive. ... More on the omim web site

Subscribe to this protein entry history

Nov. 16, 2018: Protein entry updated
Automatic update: Entry updated from uniprot information.

Feb. 2, 2018: Protein entry updated
Automatic update: Uniprot description updated

Dec. 19, 2017: Protein entry updated
Automatic update: Uniprot description updated

June 20, 2017: Protein entry updated
Automatic update: comparative model was added.

March 25, 2017: Additional information
No protein expression data in P. Mayeux work for LSM8

March 16, 2016: Protein entry updated
Automatic update: OMIM entry 607288 was added.