Figure 6. The phs1 mutation affects sphingolipid synthesis.

Sporobolomyces (Sp. sp.) wild type (IAM 13481), mutant phs1 (GI209), ura5 auxotroph (AIS2), uracil prototroph phs1+ URA5 (AIS13), and complementing strain phs1 + PHS1 (AIS15) cells and S. cerevisiae (Sa. ce.) wild type (R1158) were grown in YPD medium medium (A and B) or in SC medium lacking inositol (C) at 25°C. Cells were labeled with [³H]palmitic acid (A), [³H]dihydrosphingosine (B), or [³H]inositol (C) for 2 h. Lipids were extracted, treated with nothing or alkaline solution, and separated by normal phase TLC, followed by detection by autoradiography. Abbreviations are CER, ceramide; DHS, dihydrosphingosine; FA, fatty acid; PE, phosphatidylethanolamine; PHS, phytosphingosine; PC, phosphatidylcholine; PS, phosphatidylserine; PI, phosphatidylinositol; IPC, inositolphosphorylceramide; MIPC, mannosylinositol phosphorylceramide; LCBP, long chain base phospholipid; M(IP)2C, mannosyldiinositol phosphorylceramide. The asterisks indicate unidentified lipids.