Pre-mRNA splicing.

1. Small nuclear RNAs (snRNAs) form a complex called a spliceosome with small nuclear ribonucleoproteins (snRNPs) and other proteins.
   
   
   
   
   
   
2. The snRNAs bind to specific nucleotides in the introns of a pre-mRNA.
   
   
   
   
   
   
3. The RNA transcript is cut, releasing the introns and splicing the exons together, producing mature mRNA.