U6 snRNA-associated Sm-like protein LSm4 (LSM4) is a member of the snRNP Sm proteins family. Sm-like proteins contain the Sm sequence motif and are thought to form a stable heteromer present in tri-snRNP particles, which are important for pre-mRNA splicing. LSM4 forms a heteromer with a donut shape. The complexes are involved in various steps of RNA metabolism. LSM4 binds specifically to the 3-terminal U-tract of U6 snRNA. LSM4 contributes RNA protein interactions and structural changes which are essential during ribosomal subunit assembly.