Inosine is a non-canonical nucleoside, which is found in transfer RNAs (tRNAs) in all domains of life. tRNAs contain numerous modified nucleotides, which are essential molecules required for decoding messenger RNAs (mRNAs) into proteins. Inosine is a guanosine analog and a post-transcriptional modification. It is distributed mainly at three different sites on tRNAs: Site 34, 37, and 57 (Fig.2). Inosine 57 is only present in Archaea as 1-methylcytosine. Inosine at site 37 exists only in eukaryotic and is modified into 1-methyl inosine. Inosine (I) at site 34 is derived from genomically encoded adenosine (A) by its hydrolytic deamination. Inosine increases the ability of tRNAs to pair with synonymous codons ending in C, U, or A, and to avoid pairing with synonymous codons ending in G, thereby regulating the translation process, which is critical for cell survival. Inosine is important to balance codon usage, playing an indispensable role in life activities.
Fig.1 The structure of inosine.
Fig.2 Site of inosine on tRNAs. (Torres, et al., 2014)
Inosine is used for incorporation into the 5', 3' end, and interior of oligonucleotides.
CD BioGlyco offers a synthesis of oligonucleotides containing 2'-deoxyinosine.
Customers can choose to generate an oligonucleotide that includes inosine and add different base wobbles, depending on the base change that occurs at that position.
There are two main methods, including thin-layer chromatography which is a semi-quantitative method, and liquid chromatography coupled with mass spectrometry (LC-MS/MS) which is a highly quantitative non-radioactive method. However, these methods cannot be used in a high-throughput manner and do not give information on the location of the modified residue.
Several methods for inosine detection and quantification are based on reverse transcription (RT) of RNAs and PCR amplification. Using this method, inosine can be quantitatively detected by calculating the proportion of mismatches within the PCR product and simultaneously determining the position of the modification.
RNA containing inosine can be cleaved with specific RNases, and the digested RNA can be analyzed by gel electrophoresis. These methods are particularly useful when inosine cannot be readily tested by RT-based methods.
Fig.3 Oligonucleotide-based inosine modification and determination services. (CD BioGlyco)
CD BioGlyco also offers other Oligonucleotide-based Bases Modification Services, including Affinity-plus Base, 2'-O-methoxy-ethyl Bases (2'-MOE), 2'-O-methyl RNA Bases, and Fluoro Bases.
Inosine at the first residue of the anticodon (position 34; I34) is modified to permit recognition of three different nucleotides at the third codon position and perform the base 'wobble' and pairing, which leads to a net enhancement of the decoding capacity of a tRNA.
In eukaryotes, inosine modification can regulate the synthesis of specific proteins, making ADARs (enzymes responsible for inosine modification in mRNA) promising pharmacological targets.
Among miRNAs, inosine modification modulates miRNA functions in highly proliferative cells, including the silencing of oncogenes and tumor suppressors in various cancers, with therapeutic potential.
CD BioGlyco customizes different experimental programs to achieve the different research requirements of customs. We have first-class experimental equipment and experienced researchers to provide you with professional inosine modification and determination services. Please feel free to contact us for details if you would like to inquire about the corresponding services.
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