Overexpression of ATL2 C-terminal charge-reversal variants collapses the ER. (A) COS-7 cells overexpressing WT HA-ATL2, EER->KKE (E555K, E556K, R559E) HA-ATL2, DC HA-ATL2(1–547), or HA-ATL2 isoform 2 (see Fig. 9), fixed and costained with antibodies against HA or calnexin. Scale bar, 10 µm. (B) Quantification of cells with collapsed ER, average (± SD), >200 cells per experiment, n = 3.