Figure 5.

(A, B) Δlbp mutants are protected from loss of viability upon heat shock. (A) Yeast strains were grown in SC medium and heat-shocked at 50°C for the indicated times, and then cell growth after 24 h was determined; W303 (□), Δlbp1 (▴), and W303 cells carrying LBP1 on multicopy plasmids (•). (B) Strains were grown overnight in SC (Left) or YPD (Right), and heat-shocked for 45 min, and viability was determined. (C) Δlbp2 has reduced LCBP phosphatase activity in YPD media. W3031A (WT), Δlbp1, Δlbp2, and Δlbp1Δlbp2 strains were grown in YPD media to OD₆₀₀ of 11, and LCBP phosphatase activity was measured, as described in Materials and Methods, using sphingosine-1-³²P as substrate.