What is used to remove introns?

Introns are removed from the pre-mRNA by the activity of a complex called the spliceosome.

Understanding Intron Removal

During the process of gene expression, messenger RNA (mRNA) is initially transcribed as a precursor molecule called pre-mRNA. This pre-mRNA contains segments called introns that do not code for proteins, interspersed between coding segments called exons. To become functional mRNA, the introns must be precisely removed, and the exons must be joined together. This crucial step is performed by a molecular machine known as the spliceosome.

The Role of the Spliceosome

As stated in the provided reference, the spliceosome is the complex specifically responsible for excising introns from the pre-mRNA. This complex is not a single protein but rather a dynamic assembly of various components working in concert.

The spliceosome is composed of:

• Proteins: Numerous protein factors are involved in the recognition, assembly, and catalytic activity of the spliceosome.
• Small RNAs: Specific small nuclear RNAs (snRNAs) are key functional components. These snRNAs associate with proteins to form the core building blocks of the spliceosome.

Together, these proteins and small RNAs associate to form protein-RNA enzymes known as small nuclear ribonucleoproteins or snRNPs (pronounced SNURPS). The spliceosome is, therefore, a large ribonucleoprotein complex formed by the assembly of multiple snRNPs and associated protein factors on the pre-mRNA substrate.

This process of intron removal is called splicing, and it is essential for generating mature mRNA that can be translated into a functional protein.

In essence, the spliceosome acts like a molecular surgeon, carefully cutting out the non-coding introns and ligating the coding exons together to produce the final, continuous mRNA sequence ready for protein synthesis.