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A portion of DNA that lies between two exons, is transcribed into RNA, but does not appear in that mRNA after maturation because the intron is removed and the exons spliced together, and so is not expressed (as protein) in protein synthesis. By customary usage, the term is extended to the corresponding regions in the primary transcript of mRNA before maturation.
Synonym(s): intervening sequence
[inter- + -on]
intron/in·tron/ (in´tron) a noncoding sequence between two coding sequences within a gene, processed out in the formation of mature mRNA.
A segment of a gene situated between exons that is removed before translation of messenger RNA and does not function in coding for protein synthesis.
Etymology: L, intra, within, regin, region
a sequence of nucleotides in eukaryotic DNA that does not code for amino acids and interrupts the coding sequence of a gene. Some genes contain numerous long introns. Compare exon.
A portion of DNA that lies between two exons, is transcribed into RNA, but does not appear in that RNA after maturation, and so is not expressed (as protein) in protein synthesis.
intronA non-coding segment of a DISCONTINUOUS GENE. Introns are lengths of DNA interposed between coding segments (EXONS) in a gene and are transcribed into MESSENGER RNA but are then removed from the transcript and the exons spliced together. Introns do not contain biological information.
intronor (‘in’ for intervening) - an intervening nucleotide sequence in an INTERRUPTED split gene. Such sequences are transcribed into primary RNA transcripts, but then excised from the RNA, leaving behind the EXON sequences for the functional gene product. See RNA PROCESSING, RNA SPLICING.
untranslated, intervening sequences that are interspersed between coding sequences of a particular gene of almost all eukaryocytic genes and which are excised from the primary RNA transcript to yield mRNA.
introns are removed by the catalytic action of small nuclear riboproteins (snRNPs) which bind to special recognition sequences at the 5,(donor junction) and 3,(receptor junction) to form a complex called a spliceosome.