Production of ceramide occurs upon hydrolysis of sphingomyelin by a specific isoform of PLC, appropriately named sphingomyelinase. Nervonic ceramide (C24:1) is one of the most abundant naturally occurring ceramides. Ceramides mediate many diverse biological activities, as has been demonstrated in studies utilizing cell-permeable ceramide analogs. A few of the processes regulated by ceramides include apoptosis, cell differentiation, proliferation of smooth muscle cells, and inhibition of the mitochondrial respiratory chain.
