Two for one: regulatory RNAs that encode small proteins

RNAs are commonly categorized as being either protein-coding mRNAs or non-coding RNAs. However, an increasing number of transcripts, in organisms ranging from bacteria to humans, are being found to have both coding and noncoding functions. In some cases, the sequences encoding the protein and the regulatory RNA functions are separated, while in other cases the sequences overlap. The protein and RNA can regulate similar or distinct pathways. Here we describe examples illustrating how these dual-function (also denoted bifunctional or dual-component) RNAs are identified and their mechanisms of action and cellular roles. We also discuss the synergy or competition between coding and RNA activity and how these regulators evolved, as well as how more dual-function RNAs might be discovered and exploited.

Automated summary

RNAs can have dual functions, serving as both coding and non-coding molecules. The mechanisms of action and cellular roles of these dual-function RNAs are discussed, along with the competition or synergy between coding and RNA activity. The evolution and potential discovery of more dual-function RNAs are also explored.