snRNP Sm proteins
SMART accession number:SM00651
Description: small nuclear ribonucleoprotein particles (snRNPs) involved in pre-mRNA splicing
Interpro abstract (IPR001163):

This domain is found in Lsm (like-Sm) proteins, which have 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) ]. Other snRNPs, such as U7 snRNP, can contain different Lsm proteins.

Lsm proteins are also found in archaebacteria, which do not have any splicing apparatus, suggesting a more general role for Lsm proteins. Archaeal Lsm proteins have been shown to bind to small RNAs and are probably involved in many cellular processes [ (PUBMED:20826804) ]. Archaeal Lsm proteins are likely to represent the ancestral Lsm domain [ (PUBMED:11399068) ].

Family alignment:
View or

There are 20551 Sm domains in 20519 proteins in SMART's nrdb database.

Click on the following links for more information.