Component of the U7 snRNP complex that is involved in the histone 3'-end pre-mRNA processing. Increases U7 snRNA levels but not histone 3'-end pre-mRNA processing activity, when overexpressed. Binds specifically to the Sm-binding site of U7 snRNA. Component of the heptameric ring U7 snRNP complex. Belongs to the snRNP Sm proteins family. Extended N-terminus.