Figure 1. Antimalarial compounds synergistic with proteasome inhibitors disrupt proteostasis.

(a) Cam3.II K13 WT parasites were synchronized to the trophozoite stage (26–30 hpi) and treated with DMSO, 50 μM chloroquine (CQ), 2.5 μM WLL, 50 nM dihydroartemisinin (DHA), 500 nM OZ439, 5 μM b-AP15, or 500 nM methylene blue (MB). All treatments were at 5x IC₅₀ concentrations. Lysates were subject to Western blot and immunoblotted with antibodies against p-eIF2α, total eIF2α, K48-linked ubiquitin, and BiP. Shown is a representative blot from four independent experiments (see Supplementary Fig. 1 for replicates). (b, c) Densitometry analyses was performed using Image J to (b) assess UPR activation by normalizing p-eIF2α to total eIF2α and (c) assess proteasome inhibition by normalizing K48-Ub to the loading control BiP. Bar graphs indicate mean normalized integrated density ± S.E.M. Statistical significance was examined for each treatment against the DMSO control using a two-tailed paired t-test. *p < 0.05; **p < 0.01; ***p < 0.001; n.s. = not significant.