Small nuclear ribonucleoproteins snRNPs play a crucial role in the process of RNA splicing, which is the removal of non-coding introns from pre-messenger RNA pre-mRNA and the ligation of coding exons to form mature messenger RNA mRNA . This process is essential for proper gene expression and protein synthesis in eukaryotic cells.snRNPs are complexes composed of small nuclear RNA snRNA molecules and associated proteins. There are five major snRNPs involved in RNA splicing: U1, U2, U4, U5, and U6. These snRNPs, along with numerous other proteins, form a large ribonucleoprotein complex called the spliceosome.The spliceosome is responsible for recognizing and excising introns from pre-mRNA and joining the exons together. The process of spliceosome assembly and function can be summarized in the following steps:1. Recognition of splice sites: The U1 snRNP recognizes and binds to the 5' splice site the beginning of the intron through complementary base pairing between the U1 snRNA and the pre-mRNA. Meanwhile, the U2 snRNP binds to the branch point sequence, an adenine nucleotide located within the intron, through base pairing interactions with the U2 snRNA.2. Formation of the spliceosome: The U4/U6 and U5 snRNPs join the complex, forming the pre-catalytic spliceosome. This involves a series of RNA-RNA and RNA-protein interactions, as well as conformational changes within the snRNPs.3. Activation of the spliceosome: The U1 and U4 snRNPs are released from the complex, allowing the U6 snRNA to interact with the 5' splice site and the U2 snRNA to interact with the branch point sequence. This rearrangement leads to the formation of the catalytically active spliceosome.4. First transesterification reaction: The 2' hydroxyl group of the branch point adenine nucleotide attacks the 5' splice site, resulting in the cleavage of the 5' end of the intron and the formation of a lariat structure with the 5' end of the intron linked to the branch point.5. Second transesterification reaction: The 3' hydroxyl group of the upstream exon attacks the 3' splice site the end of the intron , leading to the cleavage of the 3' end of the intron and the ligation of the two exons.6. Release of the spliced mRNA and spliceosome disassembly: The mature mRNA, now devoid of introns, is released from the spliceosome. The snRNPs and other proteins dissociate from the mRNA and are recycled for further rounds of splicing.In summary, snRNPs are essential components of the spliceosome complex, which is responsible for the splicing of pre-mRNA. They function by recognizing and binding to specific sequences within the pre-mRNA, facilitating the assembly and activation of the spliceosome, and participating in the catalytic reactions that lead to intron removal and exon ligation.