An intergenic region is a stretch of DNA sequences located between genes.[1] Intergenic regions may contain functional elements and junk DNA. Intergenic regions should not be confused with intragenic regions (or introns), which are non-coding regions that are found within genes, especially within the genes of eukaryotic organisms.
Illustration of intergenic DNA
Schematic karyogram of a human, showing an overview of the human genome on G banding, wherein the lighter regions are generally more transcriptionally active, whereas darker regions are more inactive, including intergenic regions.
As all scientific knowledge is ultimately tentative—and in principle subject to revision given better evidence—it is possible some well-characterized intergenic regions (but also intra-genic regions like introns) may hypothetically contain as yet unidentified functional elements, such as non-coding RNA genes or regulatory sequences.[3] Such discoveries occur from time to time, but the amount of functional DNA discovered usually constitute only a tiny fraction of the overall amount of intergenic/intronic DNA.[3]
Intergenic regions in different organisms
In humans, intergenic regions comprise about 50% of the genome, whereas this number is much less in bacteria (15%) and yeast (30%).[4]
As with most other non-coding DNA, the GC-content of intergenic regions vary considerably among species. For example in Plasmodium falciparum, many intergenic regions have an AT content of 90%.[5]
Molecular evolution of Intergenic regions
As intergenic regions are a subset of the noncoding genome, the majority is thought to evolve at close to the neutral rate of mutation in species with small effective population sizes.[6] Because a large fraction of intergenic regions in such species probably consist of junk DNA (thereby explaining the overall lack of sequence conservation in this fraction), these intergenic regions are generally not maintained by natural selection and thus only experience negative selection when, by chance, gain-of-function mutations with deleterious fitness effects occur.[7]
Phylostratigraphic inference and bioinformatics methods have shown that intergenic regions can—on geological timescales—transiently evolve into open reading frame sequences that mimic those of protein coding genes, and can therefore lead to the evolution of novel protein-coding genes in a process known as de novo gene birth.[8]
^Tropp BE (2008). Molecular Biology: Genes to Proteins. Jones & Bartlett Learning. ISBN9780763709167.
^ abcAlberts, Bruce (2014). Essential Cell Biology (4th ed.). Garland Pub. pp. 172–209. ISBN978-0815345251.
^ abPallazo AF, Lee ES (January 2015). "Non-coding RNA: what is functional and what is junk?". Frontiers in Genetics. 60 (2): e1004351. doi:10.3389/fgene.2015.00002. PMC4306305. PMID 25674102.
^Francis WR, Wörheide G (June 2017). "Similar Ratios of Introns to Intergenic Sequence across Animal Genomes". Genome Biology and Evolution. 9 (6): 1582–1598. doi:10.1093/gbe/evx103. PMC5534336. PMID 28633296.
^Gardner MJ, Hall N, Fung E, White O, Berriman M, Hyman RW, et al. (October 2002). "Genome sequence of the human malaria parasite Plasmodium falciparum". Nature. 419 (6906): 498–511. doi:10.1093/molbev/msj050. PMID 16280547.
^Lynch, Michael (February 2006). "The origins of eukaryotic gene structure". Molecular Biology and Evolution. 23 (2): 450–468. doi:10.1101/gr.275638.121. PMID 34810219. S2CID 233328735.
^Pallazo AF, Gregory TR (May 2014). "The Case for Junk DNA". PLOS Genetics. 10 (5): e1004351. doi:10.1371/journal.pgen.1004351. PMC4014423. PMID 24809441.
^Papadopoulos C, Callebaut I, Gelly JC, Hatin I, Namy O, Renard M, Lespinet O, Lopes A (December 2021). "Intergenic ORFs as elementary structural modules of de novo gene birth and protein evolution". Genome Research. 31 (12): 2303–2315. doi:10.1101/gr.275638.121. PMC8647833. PMID 34810219.
External links
ENCODE threads Explorer Characterization of intergenic regions and gene definition. Nature (journal)
January 26, 2023
intergenic, region, intergenic, region, stretch, sequences, located, between, genes, contain, functional, elements, junk, should, confused, with, intragenic, regions, introns, which, coding, regions, that, found, within, genes, especially, within, genes, eukar. An intergenic region is a stretch of DNA sequences located between genes 1 Intergenic regions may contain functional elements and junk DNA Intergenic regions should not be confused with intragenic regions or introns which are non coding regions that are found within genes especially within the genes of eukaryotic organisms Illustration of intergenic DNA Schematic karyogram of a human showing an overview of the human genome on G banding wherein the lighter regions are generally more transcriptionally active whereas darker regions are more inactive including intergenic regions Further information Karyotype Contents 1 Properties and functions 2 Intergenic regions in different organisms 3 Molecular evolution of Intergenic regions 4 See also 5 References 6 External linksProperties and functions EditIntergenic regions may contain a number of functional DNA sequences such as promoters and regulatory elements enhancers spacers and in eukaryotes centromeres 2 They may also contain origins of replication scaffold attachment regions and transposons and viruses 2 Non functional DNA elements such as pseudogenes and repetitive DNA both of which are types of junk DNA can also be found in intergenic regions although they may also be located within genes in introns 2 As all scientific knowledge is ultimately tentative and in principle subject to revision given better evidence it is possible some well characterized intergenic regions but also intra genic regions like introns may hypothetically contain as yet unidentified functional elements such as non coding RNA genes or regulatory sequences 3 Such discoveries occur from time to time but the amount of functional DNA discovered usually constitute only a tiny fraction of the overall amount of intergenic intronic DNA 3 Intergenic regions in different organisms EditIn humans intergenic regions comprise about 50 of the genome whereas this number is much less in bacteria 15 and yeast 30 4 As with most other non coding DNA the GC content of intergenic regions vary considerably among species For example in Plasmodium falciparum many intergenic regions have an AT content of 90 5 Molecular evolution of Intergenic regions EditAs intergenic regions are a subset of the noncoding genome the majority is thought to evolve at close to the neutral rate of mutation in species with small effective population sizes 6 Because a large fraction of intergenic regions in such species probably consist of junk DNA thereby explaining the overall lack of sequence conservation in this fraction these intergenic regions are generally not maintained by natural selection and thus only experience negative selection when by chance gain of function mutations with deleterious fitness effects occur 7 Phylostratigraphic inference and bioinformatics methods have shown that intergenic regions can on geological timescales transiently evolve into open reading frame sequences that mimic those of protein coding genes and can therefore lead to the evolution of novel protein coding genes in a process known as de novo gene birth 8 See also EditExon Promoter biology ENCODE Heterochromatin Noncoding DNA Repetitive DNA Regulator gene Whole genome sequencingReferences Edit Tropp BE 2008 Molecular Biology Genes to Proteins Jones amp Bartlett Learning ISBN 9780763709167 a b c Alberts Bruce 2014 Essential Cell Biology 4th ed Garland Pub pp 172 209 ISBN 978 0815345251 a b Pallazo AF Lee ES January 2015 Non coding RNA what is functional and what is junk Frontiers in Genetics 60 2 e1004351 doi 10 3389 fgene 2015 00002 PMC 4306305 PMID 25674102 Francis WR Worheide G June 2017 Similar Ratios of Introns to Intergenic Sequence across Animal Genomes Genome Biology and Evolution 9 6 1582 1598 doi 10 1093 gbe evx103 PMC 5534336 PMID 28633296 Gardner MJ Hall N Fung E White O Berriman M Hyman RW et al October 2002 Genome sequence of the human malaria parasite Plasmodium falciparum Nature 419 6906 498 511 doi 10 1093 molbev msj050 PMID 16280547 Lynch Michael February 2006 The origins of eukaryotic gene structure Molecular Biology and Evolution 23 2 450 468 doi 10 1101 gr 275638 121 PMID 34810219 S2CID 233328735 Pallazo AF Gregory TR May 2014 The Case for Junk DNA PLOS Genetics 10 5 e1004351 doi 10 1371 journal pgen 1004351 PMC 4014423 PMID 24809441 Papadopoulos C Callebaut I Gelly JC Hatin I Namy O Renard M Lespinet O Lopes A December 2021 Intergenic ORFs as elementary structural modules of de novo gene birth and protein evolution Genome Research 31 12 2303 2315 doi 10 1101 gr 275638 121 PMC 8647833 PMID 34810219 External links EditENCODE threads Explorer Characterization of intergenic regions and gene definition Nature journal Retrieved from https en wikipedia org w index php title Intergenic region amp oldid 1133009360, wikipedia, wiki, book, books, library,
