phosphatidylethanolamines

Phosphatidylethanolamines (PE) are glycerophospholipids characterized by a phosphatidyl headgroup containing ethanolamine. The molecule typically has two fatty acyl chains, one at the sn-1 and one at the sn-2 position of glycerol, and may also exist as ether-linked (plasmalogen) species.

PE is a major constituent of cellular membranes in many organisms, with particularly high abundance in mitochondria and in the inner leaflet of the plasma membrane in eukaryotic cells. Its small, cone-shaped headgroup promotes negative curvature and affects membrane fusion and fission, influencing membrane dynamics and protein organization.

Synthesis: In eukaryotes PE is mainly produced through the CDP-ethanolamine Kennedy pathway in the endoplasmic reticulum. A second route is the decarboxylation of phosphatidylserine to PE by phosphatidylserine decarboxylase in mitochondria. In mammals, PE can be methylated to form phosphatidylcholine by phosphatidylethanolamine N-methyltransferase (PEMT) in the liver.

Functions: PE provides structural support for membranes, participates in protein targeting and membrane curvature, and is essential for autophagy through conjugation of LC3 to PE (LC3-PE), a key step in autophagosome formation. It also contributes to lipid signaling and remodeling processes.

Clinical and biological significance: Alterations in PE metabolism are associated with mitochondrial dysfunction, hepatic steatosis, and certain neurodegenerative disorders. In bacteria, PE is a major membrane lipid and is important for cell viability in many species.