Fig. 1

Sphingolipid metabolism pathway. Enzymes or proteins involved in sphingolipid metabolism pathways are in black type. A dotted line with a question mark means that the details are unknown. A dashed box means that the enzymes inside are not in the ER or Golgi. ER, endoplasmic reticulum; SL, sphingolipid; FA, fatty acid; LCF, long-chain fatty acid; VLCF, very-long-chain fatty acid, LCB, long-chain base; d18:0, sphinganine or dihydrosphingosine; d18:1, sphingosine; d18:2, sphingadiene; t18:0, phytosphingosine or 4-hydroxysphinganine; t18:1, 4-hydroxysphingenine; Cer, ceramide; hCer, hydroxyceramide; GlcCer, glucosylceramide; GIPC, glycosyl inositol phosphoceramide; PI, phosphatidylinositol; DAG, diacylglycerol; SPT, serine palmitoyltransferase; SPT, serine palmitoyltransferase; LCB1 and LCB2a/b, subunits of SPT; ssSPTa/b, small subunits of SPT; ORM1/2, orosomucoid-like proteins; 3-KSR, a 3-ketodihydrosphingosine reductase; SBH1/2, sphingoid base hydroxylases; Δ4-DESs, Δ4-desaturases; LOH1/2/3, ceramide synthases named LAG ONE HOMOLOGUES; ACD5, a ceramide kinase named ACCELERATED CELL DEATH 5; ACD11, a Cer-P transporter named ACCELERATED CELL DEATH 11; PLM, phloem unloading modulator; FAHs, fatty acid alphahydroxylase; CDases, ceramidases; GCS, a glucosylceramide synthase; DPL1/SPL1, a LCB-P lyase; SPP1, a phyto-S1P phosphatase; IPCS1/2/3, inositolphosphorylceramide synthases; IPUT1, an inositol phosphorylceramide glucuronosyltransferase; GMT1, a GIPC mannosyl-transferase; GINT1, a glucosamine inositol phosphorylceramide transferase; GONST1/2, Golgi-localized nucleotide sugar transporters; UGNT1, an UDP-N-acetyl-D-glucosamine transporter; GCD1/2/3/4, glucosylceramidases; GIPCPLD, a GIPC-specific phospholipase D; NPC4, a nonspecific phospholipase C4