FIG. 4.

Basal level of processed ATF6 is elevated in Perk-deficient cells. AD293 cells were cotransfected with EYFP-ATF6α and either an empty vector (Vector) or DNPerk. Empty-vector cotransfected samples were either left untreated, while samples treated with 5 mmol/l dithiothreitol (DTT) or 5 μg/ml brefeldin A (BFA) for 1 h served as controls for ATF6 induction. Immunoblotting with an antibody that recognizes YFP-tagged ATF6 shows both the ER-resident uncleaved (fl, full length) and cleaved nuclear (n) forms. Quantification of the nuclear ATF6 expressed as a percentage of the full-length form is shown below the tubulin panel.