Synonyms:HsT2456, Sm D autoantigen, Sm D1, SMD1, snRNP core protein D1, SNRPD, SNRPD1 Background:Core component of the spliceosomal U1, U2, U4 and U5 small nuclear ribonucleoproteins(snRNPs), the building blocks of the spliceosome. Thereby, plays an important role in the splicing of cellular pre-mRNAs. Most spliceosomal snRNPs contain a common set of Sm proteins SNRPB, SNRPD1, SNRPD2, SNRPD3, SNRPE, SNRPF and SNRPG that assemble in a heptameric protein ring on the Sm site of the small nuclear RNA to form the core snRNP. May act as a charged protein scaffold to promote snRNP assembly or strengthen snRNP-snRNP interactions through nonspecific electrostatic contacts with RNA.