Effect of antibodies on the initial rate of polymerization (δ au/δt)
| Treatment . | Ratio of the rates of polymerization (treatment/TRAP alone) . | Fold increase in rate of polymerization (TRAP + treatment/no TRAP) . |
|---|---|---|
| No TRAP | 0.15 ± 0.02 | 1.0 |
| TRAP | 1.0 | 6.33 ± 0.6 |
| TRAP + αArp2 (15 μg/mL or 0.1 μM) | 0.29 ± 0.04 | 2.1 ± 0.5 |
| TRAP + αp34 (15 μg/mL or 0.1 μM) | 0.82 ± 0.07 | 4.6 ± 0.5 |
| TRAP + αkaptin (15 μg/mL or 0.1 μM) | 0.936 ± 0.1135 | 5.015 ± 0.256 |
| TRAP + αArp2 (Fab) | ||
| 0.50 μg/mL (0.01 μM) | 0.55 | 4.0 |
| 5.00 μg/mL (0.10 μM) | 0.16 | 2.3 |
| 20.0 μg/mL (0.40 μM) | 0.13 | 1.9 |
| Treatment . | Ratio of the rates of polymerization (treatment/TRAP alone) . | Fold increase in rate of polymerization (TRAP + treatment/no TRAP) . |
|---|---|---|
| No TRAP | 0.15 ± 0.02 | 1.0 |
| TRAP | 1.0 | 6.33 ± 0.6 |
| TRAP + αArp2 (15 μg/mL or 0.1 μM) | 0.29 ± 0.04 | 2.1 ± 0.5 |
| TRAP + αp34 (15 μg/mL or 0.1 μM) | 0.82 ± 0.07 | 4.6 ± 0.5 |
| TRAP + αkaptin (15 μg/mL or 0.1 μM) | 0.936 ± 0.1135 | 5.015 ± 0.256 |
| TRAP + αArp2 (Fab) | ||
| 0.50 μg/mL (0.01 μM) | 0.55 | 4.0 |
| 5.00 μg/mL (0.10 μM) | 0.16 | 2.3 |
| 20.0 μg/mL (0.40 μM) | 0.13 | 1.9 |
Average (mean) change in au at 120 seconds ± SEM.
Effect of αArp2 on the rate of actin polymerization in the first 120 seconds (intensity change per second) was analyzed for 24 different experiments. Data from platelets permeabilized by sonication or by Triton were combined because results were similar. Experiments from different platelet preparations were normalized by setting the rate of increase in fluorescence (intensity units/sec) to 1.0 either for TRAP-stimulated platelets (first column) or for nonstimulated preparations (second column). For each individual measurement, the rate ratio (rate in treated sample/rate in TRAP or rate in nonstimulated samples from the same preparation) was calculated. The average rate of each treatment was derived by dividing the sum of the rate ratios for each individual measurement by the number of measurements. Note the dose response for Fab fragments: increasing amounts of Fab fragments decrease the rate of actin polymerization compared with TRAP alone.