However, mutants csg2 Δ (Csg2 is required for mannosylation of inositol phosphorylceramide (IPC)), sur1 Δ (Sur1 encodes the Mannosylinositol phosphorylceramide (MIPC) synthase catalytic subunit) and cka2 Δ (Cka2 is involved in phosphorylation of ceramide synthase), although also involved in the synthesis of complex sphingolipids, did show levels of GS activity similar to that of the wild-type strain (Fig. 6 ).
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