m7G-Quant-Seq quantifies internal N7-methylguanosine on tRNA. Targeted chemical conversion separates internal m7G from the 5' cap and records each position as a discrete signature, so the modification is detected and measured at base resolution.
Quantifying the internal m7G fraction on tRNA
N7-methylguanosine carries a positive charge on the modified guanine, which changes how the base behaves and how the surrounding structure folds. The complication in a tRNA project is the cap: both internal m7G and the cap share the same modified base, so a useful assay has to tell them apart before it can quantify anything.
Arraystar Single-Nucleotide tRNA m7G Modification Seq(m7G-Quant-Seq) is an end-to-end sample-to-data service for tRNA, from RNA sample QC and tRNA treatment through library construction, sequencing and bioinformatics. Sites are localized within mature tRNA transcripts with relative coordinates, gene attribution, anticodon and isotype, and structural-domain context.
m7G-Quant-Seq is a base-resolution method in which targeted chemical conversion distinguishes internal N7-methylguanosine from the 5' cap, so internal m7G is detected and quantified across tRNA at single-nucleotide resolution.
Standard internal m7G project — custom designs and add-on analyses available on request
| Service Name | Price |
|---|---|
| Single-Nucleotide tRNA m7G Modification Seq(m7G-Quant-Seq) |
Why internal m7G needs its own assay
Targeted conversion distinguishes the internal modification from cap structures, so the reported signal belongs to tRNA rather than to cap chemistry.
Each position yields a modification fraction, allowing internal m7G levels to be compared between samples.
No enrichment step means no pull-down bias and no cross-reactivity inside compact, structured tRNA.
Sites carry relative coordinates, host tRNA gene, anticodon, isotype and structural-domain assignment.
The quantitative conversion route provides a separate line of evidence from cleavage-based m7G sequencing.
RNA QC, tRNA treatment, library construction, sequencing and analysis are handled as one project.
Why m7G quantification is harder than it looks
Internal N7-methylguanosine modifies the base in a way that changes its charge and its stacking behaviour, and in tRNA it contributes to structure and function. Because the cap carries the same modified base, bulk signal cannot be attributed to tRNA unless the two pools are separated before detection (1).
Targeted chemical conversion acts on the internal modification and records it as a distinct reverse-transcription signature, so each internal m7G site is read at base resolution and quantified from the converted fraction. Arraystar applies the chemistry in a tRNA workflow and reports every site with its tRNA context (1).
From total RNA to internal m7G stoichiometry
Total RNA passes sample QC and small-RNA-retaining purification, then tRNA treatment and targeted chemical conversion, library construction and sequencing, after which conversion-aware alignment and per-site quantification produce the internal m7G map.
Bioinformatics for m7G-Quant-Seq
Reads are mapped to a curated tRNA reference, conversion signatures are called as internal m7G positions, and per-position stoichiometry is reported with motif, distribution, differential, enrichment and genome-browser results.
Where internal m7G quantification fits
Links internal m7G at a defined position to tRNA folding and stability.
Tests how methyltransferase or demethylase perturbations change internal m7G levels.
Separates the two pools so that tRNA-derived signal is not confused with cap signal.
Compares m7G occupancy between tRNA isotypes and isoacceptors.
Identifies differentially methylated tRNA positions between groups.
Sample handling and submission for internal m7G
| Sample Type | Notes |
|---|---|
| Whole blood | Use EDTA tubes only; heparin is not compatible with subsequent analytical procedures. |
| Cultured cells | Cell pellets are preferred to ensure high-quality material for processing. |
| Tissue | Provide fresh or frozen specimens and avoid necrotic material. |
| Total RNA | Maintain an OD 260/280 ratio ≥ 1.8 and RIN ≥ 7 with no visible degradation. Submit at least 10 µg total RNA. |
Submit at least 10 µg total RNA per sample; the amount includes material consumed by sample QC. Questions: support@arraystar.com
Questions we are asked about internal m7G quantification
Key references for internal m7G
Arraystar tRNA m7G-Quant-Seq separates internal m7G from cap signal and returns base-resolution levels — share your samples and we will scope the run.