Figure 3.

Control of ceramide transfer by PKD. PKD plays sequential roles in ceramide transfer from the ER to the Golgi. PKD stimulates PI(4)P synthesis by activating PI4KIIIβ. PI(4)P is essential for Golgi targeting of the ceramide transfer protein CERT. Golgi-localized CERT is also phosphorylated by PKD, which reduces its affinity to PI(4)P triggering dissociation from the Golgi and binding to VAP-A at the ER. VAP-A forms a ternary complex with CERT and protein phosphatase 2C-ε (PP2C- ε), which is required for dephosphorylation and release of CERT.