TABLE 5.
Zinc toxicity assay with site-directed mutations at positions Gly-280, Thr-312, and Glu-355
The viability of cells exposed to the indicated concentrations of ZnSO4 for 72 h, was determined by counting the number of viable cells using Trypan blue exclusion. Relative values presented are the mean values of three independent experiments.
| Expressed ZnT2 | ZnSO4 (μm) |
|||||
|---|---|---|---|---|---|---|
| 50 | 60 | 70 | 80 | 90 | 100 | |
| DT40 ZnT1−/−MT−/−ZnT4−/− cells | ||||||
| Untransfected | +++a | − | − | − | − | − |
| WT-HA | +++ | +++ | +++ | +++ | +++ | ++ |
| DT40 ZnT1−/−MT−/−ZnT4−/− cells | ||||||
| G280R-HA | +++ | − | − | − | − | − |
| G280A-HA | +++ | +++ | +++ | +++ | +++ | ++ |
| G280T-HA | +++ | +++ | ++ | + | − | − |
| G280L-HA | +++ | − | − | − | − | − |
| G280Q-HA | +++ | − | − | − | − | − |
| G280K-HA | +++ | − | − | − | − | − |
| DT40 ZnT1−/−MT−/−ZnT4−/− cells | ||||||
| T312M-HA | +++ | − | − | − | − | − |
| T312A-HA | +++ | − | − | − | − | − |
| T312S-HA | +++ | +++ | +++ | +++ | +++ | ++ |
| T312C-HA | +++ | +++ | +++ | ++ | + | − |
| T312D-HA | +++ | − | − | − | − | − |
| T312E-HA | +++ | − | − | − | − | − |
| DT40 ZnT1−/−MT−/−ZnT4−/− cells | ||||||
| E355Q-HA | +++ | − | − | − | − | − |
| E355A-HA | +++ | − | − | − | − | − |
| E355D-HA | +++ | + | − | − | − | − |
a The symbols represent: +++, cells growing to confluence; ++, +, decreased cell growth (20–50 or up to 20% relative to +++); −, no growth.