Increased acylation of lysophosphatidylcholine in microsomes of trembler mouse peripheral nerves

We report here the presence of a Stearoyl-CoA: [1-palmitoyl]-glycerophosphorylcholine (LPC) transacylase activity in the microsomal fraction of normal and Trembler mouse sciatic nerves. Under the experimental conditions studied as a function of incubation time, protein concentration, acyl-CoA and LPC concentrations, the transacylase specific activity was 2-3 times higher in the microsomes of the mutant's nerves than in those of the control. The addition of 5 mM ATP-Mg to the incubation medium, in the absence of bovine serum albumin, leads to a 90% decrease of the stearoyl-CoA thioesterase activity, but increases the transacylation by only 10-20%. This may be due to the low value (10 microM) of the apparent K(m) for C(18)-CoA observed for the mutant's transacylase. In microsomes from control nerves, transacylation requires exogenous LPC, whereas in Trembler mouse sciatic nerve microsomes, the transacylase can use endogenous LPC.