Figure 4. Phenotypic Analysis of Ceramide Synthase Mutants.

(A) In vitro growth of WT, Δcer1, and Δcer1+CER1 at 37°C, 5% CO₂, pH 4.0 (intracellular).

(B) In vitro growth of WT, Δcer1, and Δcer1+CER1 at 37°C, 5% CO₂, pH 7.4 (extracellular).

(C) In vitro growth of WT and Δcer1 in YPD, 30°C, 0.04% CO₂.

(D) Serial dilutions of WT, Δcer1, Δcer1 +CER1, Δcer2, and Δcer3 on solid YPD media supplemented with SDS or H₂O₂.

(E) Transmission electron microscopy of WT, Δcer1, and Δcer1 supplemented with ceramide mixture (Matreya). Bar, 500 nm.

(F) Pma1 proton pump activity of WT, Δcer1, Δcer1+CER1, and Δcer1 + C18 ceramide (Avanti Polar Lipids) measured by glucose-dependent medium acidification. Data are expressed as mean ± SEM.

For (A)–(C), data are expressed as mean ± SEM.