Sphingolipids

Sphingomyelins, the general sphingolipids have a sphingosine backbone that is shown in figure in place of the glycerol in glycerophospholipids. Such as the glycerophospholipids,   Sphingomyelins also   have   a phosphorylated   headgroup   either   choline   or ethanolamine and two hydrocarbon chains. One is a fatty acid as found in the glycerophospholipids the other is hydrocarbon chains comes from the sphingosine molecule, except which it is bonded through an amide bond in sphingolipids. They are present in the plasma membrane in the most of cells.

Figure: Structures of (a) the sphingolipids sphingomyelin and galactocerebroside; (b) cholesterol. R1 represents the hydrocarbon chain of fatty acids.

and are particularly  abundant  in the myelin sheath which surrounds  nerve cells. The  glycosphingolipids like  as the  gangliosides  and cerebrosides  are  also consequential  from sphingosine but in place of the phosphorylated  headgroup  they have one or more sugar residues.  Galactocerebrosides have a single galactose   residue and   are found   predominantly   in the neuronal   cell membranes of the brain. The gangliosides  have various sugar residues involving at  least  one  sialic  acid  (N-acetylneuraminic  acid)  residue  and  are  a  main constituent  of most  mammalian  plasma  membranes  being  particularly  abundant   in   the brain   cells. Lipid   composition    of   the   chloroplast   thylakoid membranes in plant cells is highly distinctive:  about 40 percent of the total lipids are galactolipids and 4 percent sulfolipids, with only 10 percent being phospholipids.