ALKYL-DIHYDROXYACETONEPHOSPHATE SYNTHASE

Mammalian ether phospholipids are characterized by a glycero-ether lin kage at the sn-1-position of the glycerol backbone. In humans this typ e of phospholipid species occurs mainly in the ethanolamine and cholin e phosphoglycerides comprising an estimated 15% of total phospholipids . The glycero-ether linkage is synthesized by replacement of the acyl chain in acyl-dihydroxyacetonephosphate by a long-chain alcohol that d onates the oxygen for the ether linkage. Both the enzyme that forms ac yl-dihydroxyacetone phosphate (see Chapter II of this volume) and the one that introduces the glycero-ether linkage, i.e. alkyl-dihydroxyace tonephosphate synthase, are located in peroxisomes. The deficiency of ether phospholipids in human inborn errors of metabolism, caused by de fects in peroxisome biogenesis, has clearly delineated the indispensab le role of peroxisomes in ether phospholipid synthesis. The most chara cteristic enzyme of ether lipid synthesis is alkyl-dihydroxyacetonepho sphate synthase. Its discovery and some of its properties, including m echanistic studies, have been discussed in recent reviews. This review recapitulates these findings and focuses on the new insights into the structure and properties of the enzyme that have recently been obtain ed resulting from the purification and subsequent cloning and expressi on of the cDNA encoding this peroxisomal enzyme. (C) 1997 Elsevier Sci ence B.V.