LPC acyltransferase

Microsomal fractions of oilseed rape readily incorporated (1- C) oleoyl CoA into PC, PA and TG, indicating the presence of active Kennedy pathway and PC-acyltransferase activities. Acyl transfer to PC was hugely stimulated in the presence of exogenous LPC but, in the presence of exogenous LPA the vast majority of the acyl transfer was to PA (Table 1). In each case the acylation of the added lysophospholipid was virtually the only route for oleate metabol-isation, resulting in the accumulation of labelled PC or PA over the short term. By means of pulse-chase studies, it was possible to observe some flow of label from PA towards TG and PC, which is consistent with the proposed operation of an equilibrium between DG and PC (1-4). It was more difficult to... 

The results of subcellular localisation studies are summarised in Table 2. The microsomal and oil body fractions both contained all the activities of the Kennedy pathway and had especially high LPC- and LPA- acyl transferase activities. The specific activities of the microsomal enzymes were generally higher than those of the oil bodies, but not dramatically so. The soluble fraction had high MG and DG-forming activities, but was unable to form PC or TG from oleoyl CoA. It is possible that the soluble fraction contains G3P and LPA acyltransferases but that the products are rapidly dephosphorylated to form MG and DG respectively (8). Soluble (9) and microsomal (10) G3P acyltransferases have been found in cocoa and safflower seeds respectively. 

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