Table III.
Protein kinase inhibitors prevent fast induction of high- affinity HCO3− transport
| Treatment |
K1/2
|
||
|---|---|---|---|
| Total Ci | HCO3− | CO2 | |
| μm | |||
| Control (no additions) | 28 ± 3.7 | 17 ± 2.5 | 3.5 ± 0.8 |
| Cantharidin (18 μm) | 35 ± 4.1 | 19 ± 1.1 | 5.0 ± 1.2 |
| Okadaic acid (2 μm) | 29 ± 1.4 | 14 ± 0.9 | 4.2 ± 0.5 |
| K252a (1 μm) | 202 ± 32 | 168 ± 28 | 4.8 ± 0.7 |
| Staurosporine (0.1 μm) | 153 ± 28 | 142 ± 18 | 4.4 ± 0.3 |
| Genistein (10 μm) | 167 ± 25 | 122 ± 21 | 4.9 ± 0.4 |
The effect of inhibitors of protein phosphatases (cantharidin, okadaic acid) and kinases (K252a, staurosporine, genistein) on the K1/2 values for O2 evolution, HCO3− transport, and CO2 uptake after fast induction in Synechococcus sp. strain PCC7002. Fast-induced cells were obtained from high-Ci cells (10 μg mL−1), which were allowed to run out of Ci for 4 to 8 min in the presence of CA (100 Wilbur-Anderson units mL−1) and the desired inhibitor. During the second dark period, an aliquot of the cells (8–12 μg of Chl) was centrifuged and resuspended in 4 mL of CO2-free assay buffer to enable mass spectrometric flux measurements. The data represent the mean ± sd from three independent experiments.