Component of the nuclear LSM2-LSM8 complex which is involved splicing nuclear mRNAs. LSM2-LSM8 binds directly to the U6 small nuclear RNAs (snRNAs). LSM8 is essential for the formation of the nuclear LSM2-LSM8 complex involved in the accurate splicing of selected development-related mRNAs through the stabilization of the spliceosomal U6 snRNA (PubMed:32396196). Plays a critical role in the regulation of development-related gene expression. Component of the heptameric LSM2-LSM8 complex that forms a seven-membered ring structure with a donut shape. The LSM subunits are arranged in the order LSM8, LSM2, LSM3, LSM6, LSM5, LSM7 and LSM4 (PubMed:23221597, PubMed:23620288). LSM8 subunit interacts only with its two neighboring subunits, LSM2 and LSM4 (PubMed:23221597). Interacts with the prefoldin co-chaperone subunits PFD1, PFD2, PFD3, PFD4, PFD5 and PFD6 (PubMed:32396196). A number of isoforms are produced. According to EST sequences. Expressed in roots, leaves, stems, flowers and siliques. Developmental alterations, such as reduced root length, alterations in the shape and number of cotyledons, small rosette leaves with short petioles, early flowering, short siliques with reduced seed number and frequently aborted seeds (PubMed:23221597). Lower pre-mRNA splicing events and reduced levels of U6 snRNA, but elevated levels of U4 snRNA (PubMed:32396196). Belongs to the snRNP Sm proteins family. The predicted gene has been split into 2 genes: At1g65700 and At1g65710.