Human DNA is made of long strings of three‑letter blocks called codons. Each codon tells the cell which building block, or amino acid, to add when making a protein.
Even though many different codons can code for the same amino acid, scientists used to think this was just harmless redundancy. New research shows that not all codons work the same way.
Why Some Codons Work Better
Some codons create messenger RNA (mRNA) that is stable and easy for the cell to read. These are called “optimal” codons. Others are “non‑optimal.” They make the mRNA fragile and harder for the cell to translate into protein.
Looking for the Cell’s Quality‑Control System
A team from Kyoto University and RIKEN set out to find out how cells notice weak codons. They used a genome‑wide CRISPR screen and discovered a protein named DHX29 that binds RNA.
When DHX29 was removed, mRNAs with non‑optimal codons piled up, showing that the protein normally helps get rid of them.
How DHX29 Works
Using cryo‑electron microscopy, the scientists saw DHX29 attach to the 80S ribosome—the machine that builds proteins. Further tests showed DHX29 prefers ribosomes that are reading non‑optimal codons.
DHX29 also calls in another protein team called GIGYF2‑4EHP. This duo blocks the production of the weak mRNAs, keeping the cell from wasting energy.
Why This Matters
These results change how we think about gene regulation. The choice of codon itself can turn genes on or off.
The DHX29 system may affect many processes, such as how cells become specialized, how they stay balanced, and even how cancers develop.
The researchers will keep studying DHX29 to learn more about its role in health and disease.
“Finding the factor that lets cells read this hidden layer of the genetic code is very exciting,” said lead scientist Osamu Takeuchi.