Ether lipid

Structure of an ether phospholipid. Note ether at first and second positions.
Plasmalogen. Note ether at first position, and ester at second position.
Platelet-activating factor. Note ether at first position, and acyl group at second position.

In biochemistry, an ether lipid refers to any lipid in which the lipid "tail" group is attached to the glycerol backbone via an ether bond at any position. In contrast, conventional glycerophospholipids and triglycerides are triesters.[1] Structural types include:

  • Ether phospholipids: phospholipids are known to have ether-linked "tails" instead of the usual ester linkage.[1]
    • Ether on sn-1, ester on sn-2: "ether lipids" in the context of bacteria and eukaryotes refer to this class of lipids. Compared to the usual 1,2-diacyl-sn-glycerol (DAG), the sn-1 linkage is replaced with an ester bond.[1][2][3]

Based on whether the sn-1 lipid is unsaturated next to the ether linkage, they can be further divided into alkenyl-acylphospholipids ("plasmenylphospholipid", 1-0-alk-1’-enyl-2-acyl-sn-glycerol) and alkyl-acylphospholipids ("plasmanylphospholipid"). This class of lipids have important roles in human cell signaling and structure.[4]

    • Ether on sn-2 and sn-3: this class with flipped chirality on the phosphate connection is called an "archaeal ether lipid". With few (if any) exceptions, it is only found among archaea. The part excluding the phoshphate group is known as archaeol.[5][6]
  • Ether analogues of triglycerides: 1-alkyldiacyl-sn-glycerols (alkyldiacylglycerols) are found in significant proportions in marine animals.[5]
  • Other ether lipids: a number of other lipids not belonging to any of the classes above contain the ether linkage. For example, seminolipid, a vital part of the testes and sperm cells, has a ether linkage.[1]

The term "plasmalogen" can refer to any ether lipid with a vinyl ether linkage, i.e. ones with a carbon-carbon double bond next to the ether linkage. Without specification it generally refers to alkenyl-acylphospholipids, but "neutral plasmalogens" (alkenyldiacylglycerols) and "diplasmalogens" (dialkenylphospholipids) also exist.[1] The prototypical plasmalogen is platelet-activating factor.[7]

  1. ^ a b c d e Christie W. "Ether lipids - glyceryl ethers, plasmalogens, aldehydes, structure, biochemistry, composition and analysis". www.lipidmaps.org.
  2. ^ Dean JM, Lodhi IJ (February 2018). "Structural and functional roles of ether lipids". Protein & Cell. 9 (2): 196–206. doi:10.1007/s13238-017-0423-5. PMC 5818364. PMID 28523433.
  3. ^ Ford DA, Gross RW (July 1990). "Differential metabolism of diradyl glycerol molecular subclasses and molecular species by rabbit brain diglyceride kinase". The Journal of Biological Chemistry. 265 (21): 12280–6. doi:10.1016/S0021-9258(19)38342-5. PMID 2165056. S2CID 1042240.
  4. ^ Dean, JM; Lodhi, IJ (February 2018). "Structural and functional roles of ether lipids". Protein & Cell. 9 (2): 196–206. doi:10.1007/s13238-017-0423-5. PMC 5818364. PMID 28523433.
  5. ^ a b Villanueva, Laura; von Meijenfeldt, F. A. Bastiaan; Westbye, Alexander B.; Yadav, Subhash; Hopmans, Ellen C.; Dutilh, Bas E.; Damsté, Jaap S. Sinninghe (January 2021). "Bridging the membrane lipid divide: bacteria of the FCB group superphylum have the potential to synthesize archaeal ether lipids". The ISME Journal. 15 (1): 168–182. Bibcode:2021ISMEJ..15..168V. doi:10.1038/s41396-020-00772-2. PMC 7852524. PMID 32929208.
  6. ^ "Di- and Tetra-Alkyl Ether Lipids of the Archaea". lipidmaps.org.
  7. ^ Watson RR, De Meester F, eds. (2014). Omega 3 fatty acids in brain and neurological health. Elsevier Academic Press. doi:10.1016/C2012-0-06006-1. ISBN 978-0-12-410527-0.

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