Figure 7.
Deletions in the stem domain of GPP130 abolish its sensitivity to Mn. (A) Schematic of the deletion constructs used in this figure. All deletions were made on GPP1301-247-GFP. (B) Cells were transfected with the indicated constructs, and after 24 h they were exposed to cycloheximide for 2 h then adjusted to 500 μM Mn for 2 h. After processing, GPP130 and GFP were imaged in the same cells. Thresholding was used to enhance visualization of endosome with identical thresholds applied to all constructs in a given channel. Bar, 10 μm. (C) Quantitation of the number of GFP endosomes per cell with (gray) and without (black) Mn for each GPP130 construct. GPP1301-247-GFP was also analyzed after rescue (Res.). The Mn-induced increase in GFP endosomes per cell was statistically significant for GPP1301-247-GFP, GPP1301-247-GFP rescue, and GPP130Δ2-11-GFP (mean ± SE, n > 25 cells for each construct with and without Mn; p < 0.05) but not the other stem deleted constructs (p > 0.05).