Introns are incoherent nucleotide sequences that interrupt the coding regions of genes.
They are removed from newly made RNA transcripts by a process called RNA splicing. Since most genes in multicellular organisms contain introns, their timely and precise removal is an essential biochemical process. Amazingly, some introns are capable of removing themselves. Most introns in eukaryotic nuclei, however, require the action of a spliceosome for their excision. The spliceosome is a complex macromolecular assemblage containing five small stable RNAs and a multitude of proteins, not all of which have been identified.