Figure 3.

Dose–response curve for purified IPF α. Purified bovine synaptic vesicles (50 μg of protein) were suspended in the glutamate uptake assay medium in the presence of varying amounts of fraction 31 from the Mono Q column (0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.65, 0.76, 0.86, 0.97, 1.1, 1.3, and 1.6 μg of protein). Using a molecular weight of 138,000 for IPF α, these amounts were converted to nanomoles of IPF α per liter. Uptake was allowed to proceed for 10 min at 30°C, and samples were processed as described in the text. Values for the percentage of control were calculated relative to the ATP-dependent uptake in samples containing equivalent amounts of fraction 31 from a Mono Q gradient run in the absence of loaded protein.