label: U1 small nuclear RNA
label_lc: u1 small nuclear rna
description: "The small nuclear RNA (snRNA) that is a component of U1 snRNP (small nuclear ribonucleoprotein), an RNA-protein complex that combines with other snRNPs, unmodified pre-mRNA, and various other proteins to assemble a spliceosome, a large RNA-protein molecular complex upon which splicing of pre-mRNA occurs."