L-Acylglycerol-3-phosphate

A second esterification of this type leads to a phosphatidate (enzyme l-acylglycerol-3-phosphate acyltransferase 2.3.1.51). Unsaturated acyl residues, particularly oleic acid, are usually incorporated at C-2 of the glycerol. Phosphatidates (anions of phosphatidic acids) are the key molecules in the biosynthesis of fats, phospholipids, and glycolipids. 

The first acylation, catalyzed by acyl-coenzyme A-glycerol-3-phos-phate acyl transferase (GPAT), results in the formation of 1-acyl-glycer 01-3-phosphate (lysophosphatide, LPA). The LPA serves as the substrate for the second acylation reaction, catalyzed by acyl-CoA-l-acylglycerol-3-phosphate transferase (AGPAT), to form phosphatidic acid (PA). 

Hares, W. and Frentzen, M. (1991) Substrate specificities of the membrane-bound and partially purified microsomal acyl-CoA l-acylglycerol-3-phosphate acyltransferase from etiolated shoots of Pisum sativum (L.) Planta 185, 124-iM. 

The reactions indicated by broken arrows have not yet been experimentally demonstrated. Gly-3-P, glyoerol-3-phosphate LPA, l-acylglycerol-3-phosphate PA, phosphatidic acid DG, 1,2-diacylglycerol ACP, acyl-carrier protein X, unidentified galactose carrier. 

In summary, we succeeded in the isolation of a cDNA from Limnanthes douglasii which encodes an erucoyl-CoA specific l-acylglycerol-3-phosphate acyltransferase. The deduced amino acid sequence shows substantial sequence similarity to the respective acyltransferase of E. coli. Consequently, the isolated cDNA is suitable for transforming rape-seed with the aim to increase the content of erucic acid in the fatty acid composition of rapeseed oil and, thus, to improve its industrial applicability. 

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