TABLE 1.
Rate constants of guanine nucleotide exchange reactions catalyzed by wild-type and mutant UNC-73B proteins on CeRAC
| UNC-73B | kobs (s−1, 103)a | Fold stimulationb |
|---|---|---|
| None | 0.096 ± 0.01 | |
| Wild type | 11.2 ± 0.21 | 117 |
| KR-to-AA mutant | 3.16 ± 0.026 | 32 |
| KR-to-EE mutant | 5.54 ± 0.10 | 58 |
| ΔPH mutant | 0.27 ± 0.013 | 2.8 |
| W1502A mutant | 0.12 ± 0.01 | 1.3 |
| S1216F mutant | 0.12 ± 0.01 | 1.3 |
a
The rates of release of mant-GDP from unmodified CeRAC (kobs) stimulated by approximately 0.2 μM wild-type and mutant UNC-73B proteins were determined by fitting the data from Fig. 4A as single exponential decays. Results are expressed as means ± standard deviations.
b
The fold stimulation reflects the ratio of the kobs measured for the GEF-containing reaction to that for the unstimulated reaction containing no GEF (none).