The eIF2 translation initiation factor travels to a cytoplasmic focus
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《细胞学杂志》
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 locks eIF2 in an inactive complex with eIF2B, but it is not clear whether eIF2B must be in foci for inhibition to occur.
The concentration of some eIF2B in foci might make translation more efficient or more easily regulated. The group suspects that the foci themselves move around the cell, like a mop for GDP-bound eIF2. Although no one has seen these foci in mammalian cells, they might have been easily missed: only actively translating yeast cells contained them.(Stressed yeast cells shut down general t)
The concentration of some eIF2B in foci might make translation more efficient or more easily regulated. The group suspects that the foci themselves move around the cell, like a mop for GDP-bound eIF2. Although no one has seen these foci in mammalian cells, they might have been easily missed: only actively translating yeast cells contained them.(Stressed yeast cells shut down general t)