Sphingosine 2022-03-31: reference: https://bio.libretexts.org/Bookshelves/Biochemistry/Fundamentals_of_Biochemistry_(LibreTexts)/02%3A_Unit_II-_Bioenergetics_and_Metabolism/21%3A_Lipid_Biosynthesis/21.04%3A_Biosynthesis_of_Membrane_Sphingolipids Sphingosine # It is always 18-carbon; it is synthesized from palmitoyl-CoA and Serine: Backlinks GPR12 Membrane Phospholipid Interactive Graph