Enables U1 snRNP binding activity. Predicted to be involved in spliceosomal snRNP assembly. Located in nucleus. Part of U1 snRNP. Used to study nephritis; proteinuria; and systemic lupus erythematosus. Human ortholog(s) of this gene implicated in connective tissue disease; nephritis; proteinuria; and systemic lupus erythematosus. Orthologous to human SNRPD1 (small nuclear ribonucleoprotein D1 polypeptide). [provided by Alliance of Genome Resources, Apr 2022]