DDX3X acts as a selective dual switch regulator of mRNA translation in acute ER stress.

Shawky et al. show that DDX3X selectively promotes or represses mRNA translation in a stress-dependent manner. This bidirectional regulation involves position-specific binding to the mRNA 5′ UTR and early coding region, reflecting distinct mechanisms, including initiation control during 48S scanning and translational repression associated with ac4C post-transcriptional modification.