LSM3 (U6 small nuclear RNA Associated Sm-like protein) belongs to the snRNP Sm proteins family. Sm-like proteins were identified in a variety of organisms based on sequence homology with the Sm protein family. 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.