Which one of the following involves RNA Editing?
Which one of the following involves RNA Editing?
Select an option to attempt
Correct Answer: Option A
Explanation
RNA editing is a post-transcriptional process that alters the nucleotide sequence of an RNA molecule, changing it from the sequence encoded by the genomic DNA. Mechanisms: (1) Adenosine-to-Inosine (A-to-I) editing: ADAR enzymes deaminate adenosine → inosine (read as guanosine by ribosomes), changing codon meaning (e.g. AMPA receptor GluA2 subunit: Q607R edit prevents Capermeability); (2) Cytidine-to-Uridine (C-to-U) editing: APOBEC1 enzyme complex deaminates cytidine → uridine (e.g. apolipoprotein B: CAA → UAA stop codon in intestine → ApoB-48 instead of full-length ApoB-100); (3) Insertion/deletion of uridines in kinetoplastid mitochondria. RNA editing changes mRNA sequence POST-transcriptionally, distinct from alternative splicing (which rearranges exons) or mutation (which changes DNA).