If introns are not removed from pre-mRNA, the resulting mRNA will contain non-coding sequences, which will be translated into a non-functional protein.
What are introns?
Introns are non-coding regions of DNA that are transcribed into pre-mRNA but are later removed during RNA splicing. They are found in eukaryotes and some viruses.
What is RNA splicing?
RNA splicing is a process that removes introns from pre-mRNA and joins exons together to form mature mRNA. This process is carried out by a complex molecular machinery called the spliceosome.
Consequences of Intron Retention:
- Production of Non-functional Proteins: Introns contain non-coding sequences, and if they are not removed, they will be translated into amino acids, leading to the production of a protein with an incorrect sequence. This protein will likely be non-functional.
- Disruption of Protein Structure: Introns can disrupt the reading frame of the mRNA, causing a shift in the codons and the resulting protein sequence. This can lead to a protein with a drastically altered structure and function.
- Potential for Disease: In some cases, intron retention can lead to disease. For example, mutations in the spliceosome can cause intron retention, leading to the production of abnormal proteins that can cause disease.
How is Intron Removal Ensured?
- Spliceosome Activity: The spliceosome is a highly efficient and complex machinery that accurately recognizes and removes introns from pre-mRNA.
- Quality Control Mechanisms: Cells have mechanisms to identify and degrade mRNA molecules with retained introns, ensuring that only properly spliced mRNA molecules are translated into proteins.
In summary, the removal of introns is crucial for the production of functional proteins. If introns are not removed, the resulting mRNA will be translated into a non-functional protein, potentially leading to disease.
