Component of the nuclear LSM2-LSM8 complex, which is involved in splicing of nuclear mRNAs. LSM2-LSM8 associates with multiple snRNP complexes containing the U6 snRNA (U4/U6 snRNP, spliceosomal U4/U6.U5 snRNP, and free U6 snRNP). It binds directly to the U6 snRNA and plays a role in the biogenesis and stability of the U6 snRNP and U4/U6 snRNP complexes. It probably also is involved in degradation of nuclear pre-mRNA by targeting them for decapping. LSM2-LSM8 probably is involved in processing of pre-tRNAs, pre-rRNAs and U3 snoRNA. LSM2 is required for processing of pre-tRNAs, pre-rRNAs and U3 snoRNA. Component of the heptameric LSM2-LSM8 complex that forms a seven-membered ring structure with a doughnut shape; an RNA strand can pass through the hole in the center of the ring structure. The LSm subunits are arranged in the order LSM8, LSM2, LSM3, LSM6, LSM5, LSM7 and LSM4. LSM2-LSM8 associates with PAT1 and XRN1. Component of the U4/U6-U5 tri-snRNP complex composed of the U4, U6 and U5 snRNAs and at least PRP3, PRP4, PRP6, PRP8, PRP18, PRP31, PRP38, SNU13, SNU23, SNU66, SNU114, SPP381, SMB1, SMD1, SMD2, SMD3, SMX2, SMX3, LSM2, LSM3, LSM4, LSM5, LSM6, LSM7, LSM8, BRR2 and DIB1. Present with 1440 molecules/cell in log phase SD medium. Belongs to the snRNP Sm proteins family.