FIGURE 5.

Possible involvement of endogenously accumulated PMME in the UPR level of yeast cells. (A) Wild-type (WT) yeast strain BY4741 and its cho2Δ mutant were grown in YPD medium, into which 1 mM DTT was added before further culturing for the indicated durations. The cells were then checked for HAC1-mRNA splicing. (B) BY4741 (WT) and its cho2Δ mutant were grown in YPD medium. After harvesting, their lipidic extracts were assayed for PC abundance as described in the Materials and Methods section. (C) The same experiment as shown in (A) was performed, except that SD medium containing 1 mM choline was used instead of YPD medium. (D) BY4741 cells (WT cells) were grown in YPD or SD medium containing ³²P-orthophosphate. After harvesting, their lipidic extracts were assayed for the PMME levels as shown in Supplementary Figure S1. (E) BY4741 cells (WT cells) were grown in YPD medium containing ³²P-orthophosphate, into which 1 mM DTT was added (or not added (non-stress: NS)) before further culturing for 30 min. After harvesting, their lipidic extracts were assayed for PMME levels as shown in Supplementary Figure S1. (F) BY4741 (WT) and its cho2Δ mutant were grown in YPD medium, and were stressed by a two-step addition of ethanol into the medium (culturing with 8% ethanol for 2 h followed by a 2-h culture with a higher concentration (16%) of ethanol) or remained non-stressed (NS). The cells were then checked for HAC1-mRNA splicing. ns, not significant (p > 0.05%).