A-to-I editing and the proteome
Inosine is read as guanosine, so an editing event changes the transcript itself. That makes A-to-I different from a mark that only changes how a transcript is handled: the sequence the cell and the sequencer see is no longer the sequence that was transcribed.
01The question
This line of work asks where an adenosine has been deaminated to inosine, and what that change does downstream. Because inosine is read as guanosine, an editing event can change a codon, create or remove a splice site, or alter a regulatory element.
That makes the position the whole argument. A region-level profile can say a transcript is edited; it cannot say whether the change lands in a codon or in a splice signal.
02What an editing site is read against
- Codon change. Whether a resolved site changes the encoded amino acid, which needs the site and the reading frame together.
- Splicing. Whether an editing site near a junction moves with the isoform ratio measured on the same samples.
- Transcript fate. Whether the edited version of the transcript differs in stability or translation from the unedited one.
- Enzyme dependence. Whether the site disappears when the editing enzyme is perturbed, which is what turns a site list into a mechanism.
- Protein readout. Whether the editing change is visible at the protein level, where that is measurable.
03Which route reads the mark
Ψ & Inosine Seq (BACS-seq)
Reports inosine — and pseudouridine — from a single library, at defined positions.
Site-leveltwo marks SINGLE-BASESingle-Base RNA Modification Sequencing
The other marks that read at base resolution, if the study covers more than editing.
14 methodssite-level REFERENCEModification types
How inosine differs from the marks that do not change the read.
Reference14 marks04Readouts usually run alongside
These describe the consequence of an editing event and are separate measurements, not part of the modification assay.
Expression and isoform quantification
Shows what the transcript looks like once editing is taken into account, and what the unedited version would have been.
Ribosome profiling
Reports whether the edited transcript is translated differently, for sites that change a codon.
Protein–RNA interaction profiling
Identifies which proteins sit on the edited transcript, for work that follows an editing enzyme or a reader.
05Setting the study up
- Decide whether the claim is about which transcripts are edited, or about what one edited position does.
- Resolve the mark to a position, and place it in the reading frame or the splice context it belongs to.
- Measure the consequence — isoform, translation or protein — on the same material.
- Perturb the editing enzyme if the argument is that this enzyme produced the site.
| What you want to conclude | Modification side | Request Quote |
|---|---|---|
| One position changes the read or the protein | Site-level inosine data plus a consequence readout | |
| Which transcripts are edited across samples | Position-level inosine data across the sample set | |
| The edit depends on a specific enzyme | Matched perturbed and control samples |
06FAQ
Why is A-to-I different from the other marks on this site?
Because inosine is read as guanosine, so the read has changed rather than the handling of the transcript. Other marks change how a transcript is treated; an editing event changes the sequence the cell and the sequencer see, which is why an editing claim lands on a codon or a splice signal.
Can inosine be read in the same library as pseudouridine?
Yes. The Ψ & inosine BACS-seq workflow reports both marks from one library, which is useful when a study covers both and keeps the two datasets on the same material. The two are still reported as separate marks, so neither replaces the position-level evidence the other provides.
Is a site list enough to make a mechanism claim?
No. A site list describes where editing happens; connecting it to an enzyme or to a consequence needs either a perturbation or an independent readout. The site data on its own is a description of the transcript population, and a mechanism claim rests on what changes when something in the system is changed.
What is the most common design gap here?
A resolved editing site with no reading frame or splice context attached, which leaves the consequence undetermined. The position is called correctly, but without the frame there is no way to say whether the codon changed, and without the splice context there is no way to say whether a junction moved.