Summary: A purine nucleoside that has hypoxanthine linked by the N9 nitrogen to the C1 carbon of ribose. It is an intermediate in the degradation of purines and purine nucleosides to uric acid and in pathways of purine salvage. It also occurs in the anticodon of certain transfer RNA molecules. (Dorland, 28th ed)

Top Publications

  1. Eisenberg E, Nemzer S, Kinar Y, Sorek R, Rechavi G, Levanon E. Is abundant A-to-I RNA editing primate-specific?. Trends Genet. 2005;21:77-81 pubmed
    ..The extraordinary frequency of RNA editing in human is explained by the dominance of the primate-specific Alu element in the human transcriptome, which increases the number of double-stranded RNA substrates. ..
  2. Wright D, Rice J, Yanker D, Znosko B. Nearest neighbor parameters for inosine x uridine pairs in RNA duplexes. Biochemistry. 2007;46:4625-34 pubmed
    ..ADARs act on RNA that is largely double-stranded and convert adenosine to inosine, resulting, in many cases, in an I x U pair...
  3. Kawahara Y, Zinshteyn B, Sethupathy P, Iizasa H, Hatzigeorgiou A, Nishikura K. Redirection of silencing targets by adenosine-to-inosine editing of miRNAs. Science. 2007;315:1137-40 pubmed
    Primary transcripts of certain microRNA (miRNA) genes are subject to RNA editing that converts adenosine to inosine. However, the importance of miRNA editing remains largely undetermined...
  4. Pokharel S, Beal P. High-throughput screening for functional adenosine to inosine RNA editing systems. ACS Chem Biol. 2006;1:761-5 pubmed
    ..Because inosine is decoded as guanosine, this reaction can lead to codon changes and the introduction of amino acids into a gene ..
  5. Jepson J, Reenan R. RNA editing in regulating gene expression in the brain. Biochim Biophys Acta. 2008;1779:459-70 pubmed
    Adenosine to inosine RNA editing, catalyzed by Adenosine Deaminases Acting on RNA (ADARs), represents an evolutionary conserved post-transcriptional mechanism which harnesses RNA structures to produce proteins that are not literally ..
  6. Hou B, Xu Z, Yang C, Gao Y, Zhao S, Zhang C. Protective effects of inosine on mice subjected to lethal total-body ionizing irradiation. J Radiat Res. 2007;48:57-62 pubmed
    ..To date, there are few drugs available for radioprotective therapy under such circumstances. Inosine, a natural derivative of adenosine, has been known to provide powerful protection for many kinds of cells and ..
  7. Zheng L, Gibbs M, Rodoni B. Quantitative PCR measurements of the effects of introducing inosines into primers provides guidelines for improved degenerate primer design. J Virol Methods. 2008;153:97-103 pubmed publisher
    ..b>Inosine residues are sometimes used in the primers to match variable positions within the complementary target sequences, ..
  8. Farthing D, Sica D, Hindle M, Edinboro L, Xi L, Gehr T, et al. A rapid and simple chemiluminescence method for screening levels of inosine and hypoxanthine in non-traumatic chest pain patients. Luminescence. 2011;26:65-75 pubmed publisher
    A rapid and simple chemiluminescence method was developed for detection of inosine and hypoxanthine in human plasma...
  9. Ensterö M, Akerborg O, Lundin D, Wang B, Furey T, Ohman M, et al. A computational screen for site selective A-to-I editing detects novel sites in neuron specific Hu proteins. BMC Bioinformatics. 2010;11:6 pubmed publisher
    ..enriched for A-G mismatches between the genomic template and the expressed sequence since the editing product, inosine (I), is read as guanosine (G) by the translational machinery...

More Information


  1. Qian J, Cai X, Chu J, Zhuang Y, Zhang S. Nucleotide mutations in purA gene and pur operon promoter discovered in guanosine- and inosine-producing Bacillus subtilis strains. Biotechnol Lett. 2006;28:937-41 pubmed publisher
    The promoter region of the pur operon, which contains 12 genes for inosine monophosphate biosynthesis from phosphoribosylpyrophosphate, and the purA gene, encoding the adenylosuccinate synthetase, were compared among wild-type and three ..
  2. Pullirsch D, Jantsch M. Proteome diversification by adenosine to inosine RNA editing. RNA Biol. 2010;7:205-12 pubmed
    ..We will therefore discuss the role of ADARs in proteome diversification, in particular in the nervous system where editing is most abundant. ..
  3. Lee C, Yang Y, Goodman S, Yu Y, Lin S, Kao J, et al. Endonuclease V-mediated deoxyinosine excision repair in vitro. DNA Repair (Amst). 2010;9:1073-9 pubmed publisher
    ..We also found that the 3'-exonuclease activity of DNA polymerase I is sufficient to remove the dI lesion in this minimum reconstituted assay. ..
  4. Levanon K, Eisenberg E, Rechavi G, Levanon E. Letter from the editor: Adenosine-to-inosine RNA editing in Alu repeats in the human genome. EMBO Rep. 2005;6:831-5 pubmed
    Adenosine-to-inosine (A-to-I) RNA editing increases the complexity of the human transcriptome and is essential for maintenance of normal life in mammals...
  5. Shimaoka M, Kawasaki H, Takenaka Y, Kurahashi O, Matsui H. Effects of edd and pgi disruptions on inosine accumulation in Escherichia coli. Biosci Biotechnol Biochem. 2005;69:1248-55 pubmed
    Using an inosine-producing mutant of Escherichia coli, the contributions of the central carbon metabolism for overproducing inosine were investigated...
  6. Clutterbuck D, Leroy A, O Connell M, Semple C. A bioinformatic screen for novel A-I RNA editing sites reveals recoding editing in BC10. Bioinformatics. 2005;21:2590-5 pubmed
    Recent studies have demonstrated widespread adenosine-inosine RNA editing in non-coding sequence. However, the extent of editing in coding sequences has remained unknown...
  7. Sakurai M, Yano T, Kawabata H, Ueda H, Suzuki T. Inosine cyanoethylation identifies A-to-I RNA editing sites in the human transcriptome. Nat Chem Biol. 2010;6:733-40 pubmed publisher
    Adenosine-to-inosine (A-to-I) RNA editing is a post-transcriptional processing event involved in diversifying the transcriptome responsible for various biological processes...
  8. Veres G, Radovits T, Seres L, Horkay F, Karck M, Szabo G. Effects of inosine on reperfusion injury after cardiopulmonary bypass. J Cardiothorac Surg. 2010;5:106 pubmed publisher
    b>Inosine, a break-down product of adenosine has been recently shown to exert inodilatory and anti-inflammatory properties. Furthermore inosine might be a key substrate of pharmacological post-conditioning...
  9. Li H, Zhang G, Deng A, Chen N, Wen T. De novo engineering and metabolic flux analysis of inosine biosynthesis in Bacillus subtilis. Biotechnol Lett. 2011;33:1575-80 pubmed publisher
    Wild-type B. subtilis strain W168 was de novo engineered for inosine biosynthesis. Inactivation of deoD and purA led to 0.15 ± 0.04 and 6.44 ± 0.39 g inosine/l yields, respectively. The deoD purA double mutant accumulated 7...
  10. Mabley J, Pacher P, Murthy K, Williams W, Southan G, Salzman A, et al. The novel inosine analogue INO-2002 exerts an anti-inflammatory effect in a murine model of acute lung injury. Shock. 2009;32:258-62 pubmed publisher
    Endogenous purines, including inosine, have been shown to exert immunomodulatory and anti-inflammatory effects in a variety of disease models...
  11. Mi R, Alford Zappala M, Kow Y, Cunningham R, Cao W. Human endonuclease V as a repair enzyme for DNA deamination. Mutat Res. 2012;735:12-8 pubmed publisher
    ..This is the first report of deaminated base repair activity for human endonuclease V. The relationship between the endonuclease activity and deaminated deoxyadenosine (deoxyinosine) repair is discussed. ..
  12. Módis K, Gero D, Stangl R, Rosero O, Szijarto A, Lotz G, et al. Adenosine and inosine exert cytoprotective effects in an in vitro model of liver ischemia-reperfusion injury. Int J Mol Med. 2013;31:437-46 pubmed publisher
    ..injury, we evaluated the potential cytoprotective effect of the purine metabolites, such as adenosine and inosine, and studied the mode of their pharmacological actions...
  13. Ramaswami G, Zhang R, Piskol R, Keegan L, Deng P, O Connell M, et al. Identifying RNA editing sites using RNA sequencing data alone. Nat Methods. 2013;10:128-32 pubmed publisher
    ..We also found that human genes harboring conserved editing sites within Alu repeats are enriched for neuronal functions. ..
  14. Broetto Biazon A, Bracht F, de Sá Nakanishi A, Lopez C, Constantin J, Kelmer Bracht A, et al. Transformation products of extracellular NAD(+) in the rat liver: kinetics of formation and metabolic action. Mol Cell Biochem. 2008;307:41-50 pubmed
    ..NAD(+) transformation appearing in the outflowing perfusate were nicotinamide, ADP-ribose, uric acid, and inosine. The relative proportions of these products presented some variations with the time after initiation of NAD(+) ..
  15. Jepson J, Reenan R. Genetic approaches to studying adenosine-to-inosine RNA editing. Methods Enzymol. 2007;424:265-87 pubmed
    Increasing proteomic diversity via the hydrolytic deamination of adenosine to inosine (A-to-I) in select mRNA templates appears crucial to the correct functioning of the nervous system in several model organisms, including Drosophila, ..
  16. Nilov D, Komarov D, Panov M, Karabaeva K, Mereshchenko A, Tarnovsky A, et al. Oxidation of adenosine and inosine: the chemistry of 8-oxo-7,8-dihydropurines, purine iminoquinones, and purine quinones as observed by ultrafast spectroscopy. J Am Chem Soc. 2013;135:3423-38 pubmed publisher
    ..Finally, these observations indicate that this azide might be a very useful photoaffinity labeling agent, because the reactive intermediate, adenosine iminoquinone, is such a good mimic for the universal purine base adenosine. ..
  17. Morita Y, Shibutani T, Nakanishi N, Nishikura K, Iwai S, Kuraoka I. Human endonuclease V is a ribonuclease specific for inosine-containing RNA. Nat Commun. 2013;4:2273 pubmed publisher
    ..coli endonuclease V, hEndoV as a ribonuclease specific for inosine-containing RNA...
  18. Schoft V, Schopoff S, Jantsch M. Regulation of glutamate receptor B pre-mRNA splicing by RNA editing. Nucleic Acids Res. 2007;35:3723-32 pubmed
    ..Editing of both the Q/R nucleotide and an intronic editing hotspot are required to allow efficient splicing. Inefficient intron removal may ensure that only properly edited mRNAs become spliced and exported to the cytoplasm. ..
  19. Smith J, Lunga P, Story D, Harris N, Le Belle J, James M, et al. Inosine promotes recovery of skilled motor function in a model of focal brain injury. Brain. 2007;130:915-25 pubmed
    ..In order to promote plasticity inosine was infused into the lateral ventricles for 28 days...
  20. Levanon E, Hallegger M, Kinar Y, Shemesh R, Djinovic Carugo K, Rechavi G, et al. Evolutionarily conserved human targets of adenosine to inosine RNA editing. Nucleic Acids Res. 2005;33:1162-8 pubmed
    ..The editing pattern observed suggests that some of the affected proteins might have altered physiological properties leaving the possibility that they can be related to the phenotypes of ADAR1 knockout mice. ..
  21. Shimaoka M, Takenaka Y, Mihara Y, Kurahashi O, Kawasaki H, Matsui H. Effects of xapA and guaA disruption on inosine accumulation in Escherichia coli. Biosci Biotechnol Biochem. 2006;70:3069-72 pubmed
    A xapA-disrupted mutant was studied to minimize hypoxanthine production and to improve inosine productivity in mutants of Escherichia coli. The xapA-disrupted mutant accumulated 5...
  22. Rubio M, Pastar I, Gaston K, Ragone F, Janzen C, Cross G, et al. An adenosine-to-inosine tRNA-editing enzyme that can perform C-to-U deamination of DNA. Proc Natl Acad Sci U S A. 2007;104:7821-6 pubmed
    Adenosine-to-inosine editing in the anticodon of tRNAs is essential for viability...
  23. Paz Yaacov N, Levanon E, Nevo E, Kinar Y, Harmelin A, Jacob Hirsch J, et al. Adenosine-to-inosine RNA editing shapes transcriptome diversity in primates. Proc Natl Acad Sci U S A. 2010;107:12174-9 pubmed publisher
    ..Deciphering the basis for this superiority is a long sought-after challenge. Adenosine-to-inosine (A-to-I) RNA editing is a widespread modification of the transcriptome...
  24. Athanasiadis A, Rich A, Maas S. Widespread A-to-I RNA editing of Alu-containing mRNAs in the human transcriptome. PLoS Biol. 2004;2:e391 pubmed
    ..The analysis suggests that modification of repetitive elements is a predominant activity for RNA editing with significant implications for cellular gene expression. ..
  25. George C, Wagner M, Samuel C. Expression of interferon-inducible RNA adenosine deaminase ADAR1 during pathogen infection and mouse embryo development involves tissue-selective promoter utilization and alternative splicing. J Biol Chem. 2005;280:15020-8 pubmed
    ..Two size forms of ADAR1 are known that possess adenosine-to-inosine editing activity: an interferon (IFN)-inducible approximately 150-kDa protein and a constitutively expressed N-..
  26. Wang Q, Zhang Z, Blackwell K, Carmichael G. Vigilins bind to promiscuously A-to-I-edited RNAs and are involved in the formation of heterochromatin. Curr Biol. 2005;15:384-91 pubmed heterochromatin? We report that members of the conserved Vigilin class of proteins have a high affinity for inosine-containing RNAs...
  27. Kawahara Y. Quantification of adenosine-to-inosine editing of microRNAs using a conventional method. Nat Protoc. 2012;7:1426-37 pubmed publisher
    In this protocol, I describe a method for measuring the frequency of adenosine-to-inosine RNA editing of primary, precursor and mature forms of specific microRNAs (miRNAs) derived from the same source...
  28. Risitano A, Fox K. Inosine substitutions demonstrate that intramolecular DNA quadruplexes adopt different conformations in the presence of sodium and potassium. Bioorg Med Chem Lett. 2005;15:2047-50 pubmed
    ..based on the human telomeric repeat [(GGGTTA)(3)GGG], in which one of the guanines in turn is substituted with inosine. We show that the relative stability of the substitutions is different in the presence of sodium and potassium...
  29. Ekdahl Y, Farahani H, Behm M, Lagergren J, Ohman M. A-to-I editing of microRNAs in the mammalian brain increases during development. Genome Res. 2012;22:1477-87 pubmed publisher
    Adenosine-to-inosine (A-to-I) RNA editing targets double-stranded RNA stem-loop structures in the mammalian brain. It has previously been shown that miRNAs are substrates for A-to-I editing...
  30. Ganzella M, Faraco R, Almeida R, Fernandes V, Souza D. Intracerebroventricular administration of inosine is anticonvulsant against quinolinic acid-induced seizures in mice: an effect independent of benzodiazepine and adenosine receptors. Pharmacol Biochem Behav. 2011;100:271-4 pubmed publisher
    b>Inosine (INO) has an anticonvulsant effect against seizures induced by antagonists of GABAergic system. Quinolinic acid (QA) is an agonist NMDA receptors implicated in the neurobiology of seizures...
  31. Guinzberg R, Cortes D, Díaz Cruz A, Riveros Rosas H, Villalobos Molina R, Piña E. Inosine released after hypoxia activates hepatic glucose liberation through A3 adenosine receptors. Am J Physiol Endocrinol Metab. 2006;290:E940-51 pubmed
    b>Inosine, an endogenous nucleoside, has recently been shown to exert potent effects on the immune, neural, and cardiovascular systems...
  32. Blow M, Grocock R, van Dongen S, Enright A, Dicks E, Futreal P, et al. RNA editing of human microRNAs. Genome Biol. 2006;7:R27 pubmed
    ..primary transcripts of miRNAs contain double-stranded RNA and are therefore potential substrates for adenosine to inosine (A-to-I) RNA editing...
  33. Katahira R, Ashihara H. Profiles of purine biosynthesis, salvage and degradation in disks of potato (Solanum tuberosum L.) tubers. Planta. 2006;225:115-26 pubmed
    ..following order: deoxyadenosine > adenosine > adenine > guanine > guanosine > deoxyguanosine > inosine > hypoxanthine > xanthine > xanthosine...
  34. Chen L, Carmichael G. Gene regulation by SINES and inosines: biological consequences of A-to-I editing of Alu element inverted repeats. Cell Cycle. 2008;7:3294-301 pubmed
    ..In this review we discuss the possible biological effects of Alu editing, with particular focus on the regulation of gene expression by inverted Alu repeats in the 3'-UTR regions of mRNAs. ..
  35. Habig J, Dale T, Bass B. miRNA editing--we should have inosine this coming. Mol Cell. 2007;25:792-3 pubmed
    ..In a recent issue of Science, Nishikura and colleagues provide the first evidence that editing of a microRNA (miRNA) precursor by ADARs can modulate the target specificity of the mature miRNA (Kawahara et al., 2007). ..
  36. Rula E, Emeson R. Mouse models to elucidate the functional roles of adenosine-to-inosine editing. Methods Enzymol. 2007;424:333-67 pubmed
    The conversion of adenosine to inosine (A-to-I) by RNA editing is a widespread RNA processing event by which genomically encoded sequences are altered through site-specific deamination of adenosine residue(s) in RNA transcripts through ..
  37. Tsutsumi S, Sugiura R, Ma Y, Tokuoka H, Ohta K, Ohte R, et al. Wobble inosine tRNA modification is essential to cell cycle progression in G(1)/S and G(2)/M transitions in fission yeast. J Biol Chem. 2007;282:33459-65 pubmed
    b>Inosine (I) at position 34 (wobble position) of tRNA is formed by the hydrolytic deamination of a genomically encoded adenosine (A). The enzyme catalyzing this reaction, termed tRNA A:34 deaminase, is the heterodimeric Tad2p/ADAT2...
  38. Scadden A. Inosine-containing dsRNA binds a stress-granule-like complex and downregulates gene expression in trans. Mol Cell. 2007;28:491-500 pubmed adenosine deaminases that act on RNA (ADARs), where up to 50% of adenosine (A) residues are changed to inosine (I). Traditionally, consequences of A-to-I editing were thought to be limited to modified RNA itself...
  39. Loret M, Pedersen L, Francois J. Revised procedures for yeast metabolites extraction: application to a glucose pulse to carbon-limited yeast cultures, which reveals a transient activation of the purine salvage pathway. Yeast. 2007;24:47-60 pubmed
    ..of the purine salvage pathway, as indicated by a transient drop of ATP and ADP with a concomitant rise of IMP and inosine. This metabolic perturbation was accompanied by a rapid increase in the activity of the ISN1-encoded specific IMP-..
  40. Maydanovych O, Beal P. Breaking the central dogma by RNA editing. Chem Rev. 2006;106:3397-411 pubmed
  41. Nishikura K. Editor meets silencer: crosstalk between RNA editing and RNA interference. Nat Rev Mol Cell Biol. 2006;7:919-31 pubmed
    ..A-->I RNA editing therefore seems to have additional functions, including the regulation of retrotransposons and gene silencing, which adds a new urgency to the challenges of fully understanding ADAR functions. ..
  42. Markowitz C, Spitsin S, Zimmerman V, Jacobs D, Udupa J, Hooper D, et al. The treatment of multiple sclerosis with inosine. J Altern Complement Med. 2009;15:619-25 pubmed publisher
    The objective of this study is to evaluate the safety and tolerability of inosine in patients with relapsing-remitting multiple sclerosis (RRMS)...
  43. Assaife Lopes N, Wengert M, de Sá Pinheiro A, Leão Ferreira L, Caruso Neves C. Inhibition of renal Na+-ATPase activity by inosine is mediated by A1 receptor-induced inhibition of the cAMP signaling pathway. Arch Biochem Biophys. 2009;489:76-81 pubmed publisher
    We have previously demonstrated that adenosine is deaminated to inosine in the isolated basolateral membrane (BLM) of kidney proximal tubules. This work investigates the possible effect of inosine on proximal tubule Na(+)-ATPase activity...
  44. Fisher N, Hanna P. Characterization of Bacillus anthracis germinant receptors in vitro. J Bacteriol. 2005;187:8055-62 pubmed
    ..of either proline and methionine (GerK) or serine and valine (GerL) as cogerminants in combination with inosine. The germinant specificity of GerS was refined from a previous study in a nonisogenic background since it was ..
  45. Wulff B, Nishikura K. Substitutional A-to-I RNA editing. Wiley Interdiscip Rev RNA. 2010;1:90-101 pubmed publisher
    Adenosine-to-inosine (A-to-I) editing catalyzed by adenosine deaminases acting on RNA (ADARs) entails the chemical conversion of adenosine residues to inosine residues within double-stranded RNA (dsRNA) substrates...
  46. Hsiao G, Lin K, Chang Y, Chen T, Tzu N, Chou D, et al. Protective mechanisms of inosine in platelet activation and cerebral ischemic damage. Arterioscler Thromb Vasc Biol. 2005;25:1998-2004 pubmed
    b>Inosine is a naturally occurring nucleoside degraded from adenosine. Recent studies have demonstrated that inosine has potent immunomodulatory and neuroprotective effects...
  47. Zinshteyn B, Nishikura K. Adenosine-to-inosine RNA editing. Wiley Interdiscip Rev Syst Biol Med. 2009;1:202-209 pubmed publisher
    ..The most common type of RNA editing in vertebrates is the conversion of adenosine to inosine in double-stranded RNA which occurs in the higher eukaryotes...
  48. Steward O, Sharp K, Yee K. A re-assessment of the effects of intracortical delivery of inosine on transmidline growth of corticospinal tract axons after unilateral lesions of the medullary pyramid. Exp Neurol. 2012;233:662-73 pubmed publisher
    ..Here, we repeat an experiment reporting that intracortical delivery of inosine promoted trans-midline growth of corticospinal tract (CST) axons in the spinal cord after unilateral injury to ..
  49. Alon S, Mor E, Vigneault F, Church G, Locatelli F, Galeano F, et al. Systematic identification of edited microRNAs in the human brain. Genome Res. 2012;22:1533-40 pubmed publisher
    Adenosine-to-inosine (A-to-I) editing modifies RNA transcripts from their genomic blueprint. A prerequisite for this process is a double-stranded RNA (dsRNA) structure...
  50. Iovane E, Giabbai B, Muzzolini L, Matafora V, Fornili A, Minici C, et al. Structural basis for substrate specificity in group I nucleoside hydrolases. Biochemistry. 2008;47:4418-26 pubmed publisher
    ..Here we characterize the binding interactions between the slowly hydrolyzed substrate inosine and the Escherichia coli pyrimidine-specific NH YeiK using cryotrapping and X-ray crystallography...
  51. Takahashi T, Otsuguro K, Ohta T, Ito S. Adenosine and inosine release during hypoxia in the isolated spinal cord of neonatal rats. Br J Pharmacol. 2010;161:1806-16 pubmed publisher
    Adenosine and inosine accumulate extracellularly during hypoxia/ischaemia in the brain and may act as neuroprotectants...
  52. Hornstra L, de Vries Y, Wells Bennik M, de Vos W, Abee T. Characterization of germination receptors of Bacillus cereus ATCC 14579. Appl Environ Microbiol. 2006;72:44-53 pubmed
    ..cereus ATCC 14579. In addition, the purine ribonucleosides inosine and adenosine can trigger germination of the spores. Advanced annotation of the B...
  53. Akoachere M, Squires R, Nour A, Angelov L, BROJATSCH J, Abel Santos E. Identification of an in vivo inhibitor of Bacillus anthracis spore germination. J Biol Chem. 2007;282:12112-8 pubmed
    ..This process can be triggered in vitro by the common germinants inosine and alanine. Kinetic analysis of B...