Intorns

Intorns is a nonstandard or misspelled variant of introns, the non-coding segments within genes that are transcribed into RNA but removed from the pre-mRNA during processing.

Introns are found primarily in the genomes of eukaryotes. They are transcribed along with exons but excised by RNA splicing to produce mature messenger RNA, which then guides protein synthesis. Some introns, known as group I and group II introns, are self-splicing ribozymes found in organelles, bacteria, and some eukaryotic genes. Most nuclear introns, however, are removed by the spliceosome, a large RNA-protein complex.

Splice sites at intron boundaries commonly follow the GT-AG rule in many organisms, with a donor site at the 5’ end and an acceptor site at the 3’ end; a branch point adenine participates in forming a lariat intermediate during splicing. Introns vary widely in length, from a few dozen to tens of thousands of nucleotides, and their density differs by species and gene. In addition to their role in separating coding sequences, introns can influence gene expression through alternative splicing, enabling a single gene to produce multiple protein isoforms and contributing to proteomic diversity.

Evolutionary perspectives on introns include debates between intron-early and intron-late models, and many introns are thought to have originated from mobile genetic elements. There is also interest in the regulatory elements introns may harbor, which can affect transcription, mRNA export, and translation.

Medical relevance is notable: mutations at splice sites or in regulatory intronic regions can disrupt gene expression and cause disease. Therapeutic strategies, such as antisense oligonucleotides, aim to modulate splicing in certain genetic conditions.

Discovery and naming: the concept of split genes and introns emerged in the 1970s, with Nobel Prize recognition in later years for work illuminating RNA processing and gene structure.