FIGURE 11.

Time course for transacylation activity of ScGPCAT in the presence of added LPC. Shown is incorporation of ¹⁴C activity from [¹⁴C]choline-labeled GPC (1 mm) into lipids in the presence of non-radioactive 18:1-LPC (0.5 mm) and microsomal fractions (40 μg of protein). Microsomal fractions were from an ale1Δ gpc1Δ strain overexpressing GPC1(ScGPCAT) or from an ale1Δ strain expressing EV. LPC constituted 98–99% and PC constituted 1–2% of the radioactive chloroform-soluble lipids after 40 min. The activity of ScGPCAT during the first 10 min, calculated on the formed radiolabeled LPC, was 9.5 nmol/min/mg protein. Corresponding incubations with microsomes prepared from ale1Δ gpc1Δ transformed with empty vector gave no incorporation of radioactivity into the chloroform phase, indicated with a star at 40 min of incubation in the graph. Data are given for triplicate assays ± S.D. (error bars).