Pre-mRNA splicing is an important process to mature transcripts into mRNA that can be exported from the eukaryotic nucleus for translation.
Using U-rich snurps to form the spliceosome complex, the intronic regions of DNA can be excised. U1 binds to the start of the intron, and U2 at the end. This provides binding sites for the spliceosome to form around, with U4, U5, and U6 then binding. U1 and U4 are removed, forming the final catalytic complex. This allows a lariat loop to be formed, with the branch point adenosine being used to excise it. This process uses ATP hydrolysis, in a molecular turnstile mechanism, as a kinetic proofreading process. This prevents poorly aligned snurps from becoming catalytically active and cleaving DNA incorrectly. If the spliceosome is not aligned correctly, it will detach and separate.
By using proofreading mechanisms, the cell can ensure pre-mRNA is spliced correctly, preventing issues.
Splicing is a necessary process for pre-mRNA to undergo in order to allow nuclear export. During splicing, protein factors, including NXF1, are attached to the matured mRNA, allowing it to pass through nuclear pore complexes. This is necessary in eukaryotic organisms, where transcription and translation occur in different compartments (nucleus vs cytoplasm).
