Stabilizing effect of apoA-I on PLTP activity. PLTP was incubated at 58°C for 1 hour in the presence or absence of 20 μg apoA-I and assayed for the phospholipid transfer activity. Figure is representative for two independent experiments performed with two different PLTP batches. Bars represent mean ± SD calculated from duplicates. *20 μg apoA-I was added to PLTP after the incubation at 58°C for 1 hour.