Spleißprozesse

Spleißprozesse, also known as splicing processes, are a fundamental aspect of molecular biology, particularly in eukaryotes. They refer to the cellular mechanisms by which introns, non-coding intervening sequences within a pre-messenger RNA (pre-mRNA) molecule, are removed and exons, the coding sequences, are joined together to form a mature messenger RNA (mRNA). This process is crucial for generating functional proteins.

The process of splicing is carried out by a large molecular machine called the spliceosome. The spliceosome is composed of small nuclear ribonucleoproteins (snRNPs), which themselves are complexes of small nuclear RNAs (snRNAs) and proteins. These snRNPs assemble on the pre-mRNA, recognizing specific sequences at the boundaries of introns and exons. The spliceosome then catalyzes two transesterification reactions that excise the intron and ligate the adjacent exons.

Alternative splicing is a significant variation of this process. In alternative splicing, different combinations of exons from a single pre-mRNA can be included or excluded in the final mature mRNA. This allows a single gene to produce multiple different protein isoforms, greatly increasing the protein diversity encoded by a genome without requiring a proportional increase in the number of genes. This mechanism plays a vital role in cellular differentiation and development. Errors in splicing can lead to the production of non-functional proteins and are implicated in various human diseases.