alkyllipid

An alkyllipid is a lipid molecule in which an alkyl chain is linked to a lipid backbone by an ether bond rather than an ester bond. The term is commonly used to describe ether lipids, a diverse class that includes alkylglycerols, alkylacylglycerophospholipids, and vinyl-ether analogues such as plasmalogens.

In alkylglycerolipids, one fatty-type substituent at the sn-1 position is an alkyl (or alkenyl) ether chain, while other positions may carry further substituents such as another fatty acyl group or a phosphate headgroup. Notable members include alkylglycerols (glycerol ethers), glycerophospholipids bearing an ether linkage (alkylphospholipids), and vinyl-ether lipids (plasmalogens). Platelet-activating factor is a well-known ether lipid: 1-alkyl-2-acetyl-sn-glycero-3-phosphocholine.

Biosynthesis occurs largely in peroxisomes, where the initial ether bond is formed, followed by remodeling in the endoplasmic reticulum. Ether lipids are widespread in bacteria, archaea, and eukaryotes, with particularly high abundance in mammalian tissues such as brain and heart.

Functions attributed to alkyllipids include contributions to membrane structure and fluidity, roles as reservoirs for signaling molecules, and protection against oxidative damage. Abnormal ether lipid metabolism is associated with peroxisomal disorders and has been linked to some neurodegenerative conditions in observational studies.