RNA Splicing Process

Overview

• Purpose of RNA Splicing: To remove non-coding regions (introns) from the RNA transcript, leaving only the protein-coding regions (exons).

Key Terms

• Introns: Non-coding regions in the RNA, shown in green.
• Exons: Protein-coding regions in the RNA, shown in yellow.
• Spliceosome: A complex assembly of proteins and RNA molecules responsible for splicing.

Splicing Process

1. Assembly of Splicing Factors:

   • Helper proteins assemble at the intron/exon borders.
   • These proteins act as beacons to guide small nuclear ribonucleoproteins (snRNPs).

2. Formation of the Spliceosome:

   • snRNPs and splicing factors form the spliceosome.

3. Exon Bridging:

   • The spliceosome brings the exons on either side of the intron close together.

4. Intron Loop Formation:

   • One end of the intron is cut and folded back to form a loop.

5. Exon Joining:

   • The spliceosome cuts the RNA to release the intron loop.
   • The two exons are joined together.

Completion

• The edited RNA and the intron loop are released.
• The spliceosome disassembles.
• This process is repeated for every intron in the RNA.

Example

• Multiple spliceosomes (in purple) assemble along the RNA.
• Each spliceosome removes one intron by releasing the loop before disassembling.
• In the given example, three introns are removed to produce complete protein instructions.

Visualization

• The process can be visualized in real-time animations showing the assembly and disassembly of spliceosomes and the excision of introns.