Relevant substrates and products for our study of SicTox enzymes. The reaction at left shows conversion of sphingolipid substrates to cyclic ceramide phosphate; the reaction at right shows conversion of lysophospholipid substrates to cyclic phosphatidic acid. R1, R2, and R3 represent alkyl chains of varying length. The four different headgroup alcohols (XOH) represented here are choline (SM and LPC), ethanolamine (CPE and LPE), glycerol (LPG), and serine (LPS).