RNAmuokkauksia

RNAmuokkauksia, often translated as RNA editing, is a post-transcriptional modification process that alters the nucleotide sequence of RNA molecules. This alteration can lead to a change in the information encoded by the RNA, potentially resulting in a different protein product than that encoded by the original gene.

The most common forms of RNA editing in eukaryotes are A-to-I (adenosine to inosine) and C-to-U (cytidine to uridine) conversions. In A-to-I editing, an enzyme called ADAR (adenosine deaminase acting on RNA) catalyzes the deamination of adenine to inosine. Inosine is recognized by the cellular machinery as guanosine, thus effectively changing an A codon to a G codon. C-to-U editing is mediated by APOBEC (apolipoprotein B mRNA editing enzyme, catalytic polypeptide) family enzymes, which deaminate cytidine to uridine.

RNA editing is a widespread phenomenon, occurring in various organisms including plants, fungi, protists, and animals. It plays crucial roles in diverse biological processes. For example, in mammals, A-to-I editing of neurotransmitter receptor mRNAs can alter their ion channel properties, affecting neuronal signaling. In plants, C-to-U editing in chloroplast and mitochondrial transcripts is essential for the proper function of these organelles.

The discovery of RNA editing highlights the complexity of gene expression regulation beyond DNA sequence. It provides a mechanism for generating genetic diversity from a single gene, allowing for functional diversification and adaptation. Dysregulation of RNA editing has been implicated in various human diseases, underscoring its importance in cellular homeostasis.