Component of LSm protein complexes, which are involved in RNA processing and may function in a chaperone-like manner. Component of the cytoplasmic LSM1-LSM7 complex which is involved in mRNA degradation by activating the decapping step. 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, 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 binds specifically to the 3'-terminal U-tract of U6 snRNA. LSM2-LSM8 probably is involved in processing of pre-tRNAs, pre-rRNAs and U3 snoRNA. LSM2, probably in a complex that contains LSM2-LSM7 but not LSM1 or LSM8, associates with the precursor of the RNA component of RNase P (pre-P RNA) and may be involved in maturing pre-P RNA. LSM2 is required for processing of pre-tRNAs, pre-rRNAs and U3 snoRNA. Component of the heptameric LSM1-LSM7 complex that forms a seven-membered ring structure with a doughnut shape. The LSm subunits are arranged in the order LSM1, LSM2, LSM3, LSM6, LSM5, LSM7 and LSM4. Except for LSM1, where a C-terminal helix crosses the ring structure to form additional interactions with LSM3 and LSM6, each subunit interacts only with its two neighboring subunits. The LSM1-LSM7 complex interacts with PAT1; within the complex PAT1 has direct interactions with LSM2 and LSM3. 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. A complex comprising LSM2-LSM7 without LSM1 or LSM8 may exist. Likewise, LSM2 and LSM3 can assemble into a doughnut structure that binds PAT1 (in vitro). 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 2210 molecules/cell in log phase SD medium. Belongs to the snRNP Sm proteins family.