The eIF2 translation initiation factor travels to a cytoplasmic focus for activation, according to Campbell et al. (page 925). In stressed cells, which turn down translation, the same foci soak up eIF2.
Stressed yeast cells shut down general translation so they can concentrate on making proteins that will help them adapt. One highly regulated protein during this inhibition is eIF2, which is active only in its GTP-bound form. The GDP-to-GTP exchange is done by eIF2B, about half of which the authors now show aggregates in a cytoplasmic blob in yeast.
Under normal conditions, eIF2 shuttled quickly in and out of the foci, presumably getting activated and sent on its way. But when cells were stressed (e.g., by low amino acid levels), eIF2 was less able to escape the foci. This trapping depended on eIF2 phosphorylation. Translation inhibition also depends on eIF2 phosphorylation, which...
