Figure 3. Expression levels of ER stress-responsive proteins in prion infected GRP78^+/+ and GRP78^+/− mice.

(A) Protein expression levels of UPR signaling proteins and ER chaperones from brains of GRP78^+/+ and GRP78^+/− mice infected with prions were examined by Western blot. Proteins analyzed included GRP78, GRP94, PDI, IRE1, CHOP, PERK, eIF2α, calnexin, calreticulin as well as the phosphorylated forms of PERK and eIF2α. PrP^Sc content was assessed after treating brain extracts with PK as explained in Experimental Procedures. β-actin is shown as a loading control. Numbers at the top of the panel represent samples from three different animals in each group. For all samples, the same amount of total protein was loaded in each lane. For space constrains blots were cropped, but all samples were run using the same conditions and in the same gel. (B) Quantifications of Western blot signals from 3 replicates of the experiment shown in panel A are represented as averages ± standard errors. Statistical differences were analyzed by using student’s t-test. *P < 0.05, ***P < 0.001.