Fig. 3: Central amino acid residues can modulate DDX39A and DDX39B heat shock A-body targeting.

a Schematic indicating the positions of unique residues within the DDX39 proteins (black bars, top panel). The sequences of the central region (amino acids 100-250) are provided, with amino acid differences highlighted in gray (lower panel). b MCF-7 cells were transfected with mutant DDX39A-GFP constructs containing individual substitutions corresponding to the 17 residue differences in the amino acid 100-250 region. Cells were heat shock-treated and A-body targeting efficiency was calculated. 10 cells were analyzed per replicate, and values represent means ± s.e.m (n  =  3 independent experiments, a two-tailed Student’s t test was used: *p ≤ 0.05). c DDX39A-mCherry (red) and DDX39A(F184L)-GFP or DDX39A(C223V)-GFP (green) constructs were expressed in MCF-7 cells exposed to heat shock (top) or acidotic (bottom) conditions. Representative images are presented. d Heat shock-treated MCF-7 cells expressing the indicated DDX39B mutations were quantified for A-body targeting. 10 cells were analyzed per replicate, and values represent means ± s.e.m. (n  =  3, independent experiments, a two-tailed Student’s t test was used: *p ≤ 0.05). e Representative images were taken of the indicated DDX39B-GFP point mutations. DDX39B-mCherry was included as a control. f MCF-7 cells transfected with the indicated DDX39B mutants were subjected to heat shock treatment prior to lysate fractionation. Western blotting was used to determine the presence of the indicated DDX39B-GFP constructs in the insoluble fraction, with GAPDH and Histone H3 used as soluble and insoluble controls, respectively. In representative images, dashed circles represent nuclei, selected regions (white boxes) were expanded below (merge: far-right). white scale bars represent 10 μm. Source data for all graphs and blots are provided with this paper.