Is the error rate of RNA transcription high?

Yes, RNA transcription has a high error rate.

The high error rate in RNA transcription is due to the lack of proof-reading activity in RNA polymerase, the enzyme that’s responsible for RNA transcription. The lack of proof-reading activity means RNA polymerases cannot correct the mistakes they make.

Researchers have found that the severity of the mistakes made by RNA polymerase is influenced by where the mistake is in the mRNA. Errors in certain parts of the mRNA may result in only a small, insignificant change to the protein encoded by the gene while others can alter how the whole instruction is edited later.

Transcription errors are generally transient, affecting only a subset of the encoding proteins unlike replication errors that are more likely to be transmitted to subsequent generations. However, because individual transcripts can be translated multiple times, a single small error can have a considerable effect on the pool of proteins.

Transcription errors may also contribute to cellular noise, impacting cell survival under stressful circumstances.