FIG 6.

ATP and Ca²⁺ restore EIAV Env production in SYNJ2BP KO HEK293T cells. (A) Extraction of the same amounts of ER from cells overexpressing SYNJ2BP and KO cells. The ER extraction process is described in Materials and Methods. The lysates from the cytoplasm (Cyt) and the ER were analyzed by using Western blotting to detect the ER internal reference protein calnexin. (B or C) Supplementation of the cell culture with ATP or CaCl₂ can increase the levels of ATP or Ca²⁺ in the ER in SYNJ2BP KO HEK293T cells, as presented by the histogram. The detection of levels of ATP or Ca²⁺ in the ER is described in Materials and Methods. The data represent the means ± the SEM from three independent experiments (***, P < 0.001; **, P < 0.05). EIAV Env production in WT or SYNJ2BP KO HEK293T cells with or without supplement of ATP or CaCl₂ was measured by Western blotting. The results of the densitometry analysis to quantify the ratio of Env to β-actin are shown at the bottom (lane 1 set as 1.0).