https://phys.org/news/2018-07-hidden-rnas-protein-synthesis.html

In a new study published in Nature, scientists describe how the protein-making machinery identifies alternative initiation sites from which to start protein synthesis. "We discovered a mechanism that explains how sites are chosen for translation events that occur in regions that are traditionally considered untranslated and that initiate at non-traditional start sites," said senior author Eckhard Jankowsky, Ph.D., professor in the Center for RNA Molecular Biology at Case Western Reserve University School of Medicine. "Over the last several years it has become clear that translation in these regions is pervasive, but it is poorly understood how start sites are chosen among the millions of possible start sites."

In the new study, Jankowsky's team leveraged an enzyme that is part of the protein-making machinery—called Ded1p. Mutations in the human version of Ded1p are linked to tumors and cognitive disabilities. Viruses often target the critical enzyme to disrupt protein synthesis inside cells. Jankowsky's team created yeast cells with defective Ded1p. The use of alternative start sites for protein synthesis, like AUA or AAG, dramatically increased in these cells. However, the cells only used a small fraction of possible alternative sites.