U1 small nuclear ribonucleoprotein–precursor messenger RNA complex (U1 snRNP–pre-mRNA complex)

The **U1 small nuclear ribonucleoprotein–precursor messenger RNA complex** forms when the U1 snRNP, an RNA–protein assembly comprising U1 snRNA, ten proteins including U1-70K, U1-A, U1-C, and seven Sm proteins, binds the 5′ splice site region of a pre-mRNA molecule[1][3][5][6][7]. This interaction initiates the assembly of the spliceosome and marks the site for intron excision, a crucial step in eukaryotic gene expression. Besides its canonical splicing role, the U1 snRNP–pre-mRNA complex prevents premature cleavage and polyadenylation within introns and regulates mRNA length, impacting gene output and alternative splicing (“U1 telescripting”)[2][6][8]. Defective U1 snRNP function or abundance can cause widespread mis-splicing and disease, including neurodegenerative disorders, cancers, and autoimmune syndromes[2][4]. The complex itself is not typically a direct drug target, but its functional modulation is of interest for diseases associated with splicing abnormalities[2][4].

Other names

U1 snRNP: U1 small nuclear ribonucleoproteinSpliceosomal U1 snRNPU1 snRNA/protein complexU1/pre-mRNA recognition complex

Antisense oligonucleotides block U1 snRNA base pairing, inhibiting splicing and/or causing premature cleavage/polyadenylation Splicing inhibitors (generally act on the spliceosome; U1 effects may be indirect)