The process that removes introns is called splicing.
Splicing is a crucial step in gene expression, occurring after transcription and before translation. During splicing, non-coding sequences called introns are removed from the pre-mRNA molecule, leaving only the coding sequences (exons) to be translated into protein.
The process of splicing is carried out by a complex machinery called the spliceosome. This complex is made up of proteins and small nuclear RNAs (snRNAs) that recognize specific sequences at the intron-exon boundaries. The spliceosome then cuts out the introns and joins the exons together, producing a mature mRNA molecule ready for translation.
Examples of Splicing
- Alternative splicing: A single gene can produce multiple different proteins by splicing its pre-mRNA in different ways. This allows for greater diversity in protein production from a limited number of genes.
- Intron retention: Sometimes, introns are not completely removed, resulting in the inclusion of intronic sequences in the mature mRNA. This can have various effects on gene expression.
