Glycerolipid synthesis by homogenate and oil bodies from developing mustard (Sinapis alba L.) seed.

[1-(14)C]Oleic acid and [14-(14)C]erucic acid were converted to their acyl-CoA derivatives and incorporated into acyl lipids by a homogenate from developing mustard (Sinapis alba L.) seed and oil bodies, as well as supernatant isolated by centrifugation at 20000 g. In both homogenate and oil bodies, the oleoyl moieties from exogenous [1-(14)C]oleoyl-CoA were most extensively incorporated into phosphatidic acids, but very little into phosphatidylcholines. The pattern of labelling of acyl lipids by oleoyl versus erucoyl moieties from either of the corresponding fatty acids, added individually or as a mixed substrate, indicates that oleoyl-CoA directly acylates sn-glycerol-3-phosphate to yield lysophosphatidic acids and phosphatidic acids that are subsequently converted to mono- and diacylglycerols. In contrast, erucoyl-CoA predominantly acylates preformed mono-and diacylglycerols containing oleoyl moieties to yield triacylglycerols containing erucoyl moieties.