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Last Updated: 2019-08-16
Plasmalogens are a class of phospholipids found in animals. Plasmalogens are thought to influence membrane dynamics and fatty acid levels, while also having roles in intracellular signalling and as antioxidants. Plasmalogens consist of a glycerol backbone with an vinyl-ether-linked alkyl chain at the sn-1 position, an ester-linked long-chain fatty acid at the sn-2 position, and a head group attached to the sn-3 position through a phosphodiester linkage. It is the vinyl-ether-linkage that separates plasmalogens from other phospholipids. Plasmalogen biosynthesis begins in the peroxisomes, where the integral membrane protein dihydroxyacetone phosphate acyltransferase (DHAPAT) catalyzes the esterification of the free hydroxyl group of dihydroxyacetone phosphate (DHAP) with a molecule any of long chain acyl CoA. Next, alkyl-DHAP synthase, a peroxisomal enzyme associated with DHAPAT, replaces the fatty acid on the DHAP with a long chain fatty alcohol. The third step of plasmalogen biosynthesis is catalyzed by the enzyme acyl/alkyl-DHAP reductase, which is found in the membrane of both the peroxisome and endoplasmic reticulum (ER). Acyl/alkyl-DHAP reductase uses NADPH as a cofactor to reduce the ketone of the 1-alkyl-DHAP using a classical hydride transfer mechanism. The remainder of plasmalogen synthesis occurs using enzymes in the ER. Lysophosphatidate acyltransferases (LPA-ATs) transfer the acyl component of a polyunsaturated acyl-CoA to the the 1-alkyl-DHAP, creating a 1-alkyl-2-acylglycerol 3-phosphate. The phosphate is then removed by lipid phosphate phosphohydrolase I (PAP-I), and the head group is attached by a choline/ethanolaminephosphotransferase. The majority of plasmalogens have either ethanolamine or choline as a headgroup, although a small amount of serine and inositol-linked ether-phospholipids can also be found. In the final step, the vinyl-ether linkage is created by plasmanylethanolamine desaturase, which catalyzes the formation of a double bond in the alkyl chain of the plasmalogen.
Plasmalogen Synthesis References
Harhay GP, Sonstegard TS, Keele JW, Heaton MP, Clawson ML, Snelling WM, Wiedmann RT, Van Tassell CP, Smith TP: Characterization of 954 bovine full-CDS cDNA sequences. BMC Genomics. 2005 Nov 23;6:166. doi: 10.1186/1471-2164-6-166.Pubmed: 16305752
Mistry DH, Medrano JF: Cloning and localization of the bovine and ovine lysophosphatidic acid acyltransferase (LPAAT) genes that codes for an enzyme involved in triglyceride biosynthesis. J Dairy Sci. 2002 Jan;85(1):28-35. doi: 10.3168/jds.S0022-0302(02)74049-6.Pubmed: 11860120
This pathway was propagated using PathWhiz - Pon, A. et al. Pathways with PathWhiz (2015) Nucleic Acids Res. 43(Web Server issue): W552–W559.
Propagated from SMP0000479
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