U1 small nuclear ribonucleoprotein complex (U1 snRNP)

The U1 small nuclear ribonucleoprotein (U1 snRNP) complex is a major component of the spliceosome, the molecular machine responsible for removing introns from pre-mRNA [1, 4]. It is composed of the U1 small nuclear RNA (snRNA), a core of seven Sm proteins, and three specific proteins: U1-70K, U1A, and U1C [2, 4]. The primary function of U1 snRNP is to recognize and bind the 5' splice site of introns through base-pairing with the U1 snRNA, thereby initiating spliceosome assembly [4, 12]. Additionally, it plays a vital role in "telescripting," a process that prevents premature polyadenylation and ensures the transcription of long genes [1, 13]. Mutations or functional defects in U1 snRNP are implicated in neurodegenerative diseases such as Spinal Muscular Atrophy (SMA) and Amyotrophic Lateral Sclerosis (ALS), as well as in various cancers [3, 6, 14]. Therapeutically, U1 snRNP is targeted by small molecule splicing modulators like Risdiplam and Branaplam, which enhance its binding to specific splice sites to correct genetic defects [8, 9]. It is also a well-known autoantigen in systemic autoimmune diseases, where anti-U1 RNP antibodies serve as diagnostic markers [2].

Other names

U1 snRNPU1 ribonucleoproteinU1 small nuclear ribonucleoprotein particleU1 RNP

Splicing modulation by stabilizing the interaction between the U1 snRNP complex and the 5' splice site of pre-mRNA to promote exon inclusion.