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. 2021 Jan 23;296:100335. doi: 10.1016/j.jbc.2021.100335

Figure 2.

Figure 2

Basal UPR is suppressed in high PC levels. A, phospholipid composition in ER-enriched microsome fraction from wild-type (WT) cells grown to log phase in SCD medium with or without 1 mM choline. Data represent mean ± SD (n = 3). B, PE/PC ratio in ER-enriched microsome fraction from WT with or without choline. C, WT cells expressing 4xUPRE-GFP grown to log phase in SCD medium with or without 1 mM choline were subjected to Western blotting. Pgk1 and ponceau staining were monitored as a loading control. D, GFP in (C) was quantified. GFP signals were normalized to Pgk1 and expressed relative to WT cells (set as one). Data represent mean ± SD (n = 3). E, WT cells expressing Ire1(ΔIII)-3HA-GFP and 4xUPRE-GFP grown to log phase in SCD medium with or without 1 mM choline were subjected to Western blotting. F, GFP in (E) was quantified as described in (D). Data represent mean ± SD (n = 3). G, phospholipid composition in ER-enriched microsome fraction from WT, ups1Δ, cho2Δ and ups1Δcho2Δ (ΔΔ) cells grown to log phase in SCD medium. Data represent mean ± SD (n = 3). ∗p < 0.05, ∗∗p < 0.01. H, PE/PC ratio of ER-enriched microsome fraction from WT, ups1Δ, cho2Δ and ups1Δcho2Δ (ΔΔ) cells. I, WT, cho2Δ, opi3Δ, ups1Δ, ups1Δcho2Δ, and ups1Δopi3Δ cells expressing 4xUPRE-GFP grown to log phase in SCD medium were subjected to Western blotting. J, GFP in (I) was quantified as described in (D). Data represent mean ± SD (n = 3). ER, endoplasmic reticulum; PC, phosphatidylcholine; PE, phosphatidylethanolamine; SCD, synthetic complete glucose; UPR, unfolded protein response; UPRE, UPR element.