Figure 2.

Stress granule (SG) nucleation, eukaryotic initiation factor 2α (eIF2α) phosphorylation, and global translation. Transient expression of (A) SG-nucleating proteins T-cell intracellular antigen 1 (TIA1), or (B) FMRP autosomal homolog 1 (FXR1) in COS7 cells triggers eIF2α phosphorylation (red) and prevents translation (blue in merged figure, shown separately in gray), as shown by labeling with the amino acid analog l-azidohomoalanine (AHA) in some transfectants (white arrows) but not those lacking SGs (green arrow). Overexpression of GTP-activating protein-binding protein 1 (G3BP1) (C,D) can nucleate SGs before/without triggering eIF2α phosphorylation or translational arrest (green arrows). Yellow indicates red/green colocalization.