Table 1.
Transducin activation by mutant opsins in the presence of C9-retinal analogues measured in COS cell membranes
| Mutant | 11-cis-Retinal, Dark* | 11-cis-9-Ethylretinal
|
11-cis-9-Propylretinal
|
||
|---|---|---|---|---|---|
| Dark* | Light† | Dark* | Light† | ||
| Wild type | 0.8 ± 0.2 | 5.4 ± 1.2 | 80.2 ± 19.5 | 11.2 ± 5.3 | 55.9 ± 10.5 |
| G121A | 2.3 ± 1.3 | 4.6 ± 1.2 | 86.1 ± 6.3 | 7.6 ± 0.6 | 78.6 ± 7.2 |
| G121S | 5.0 ± 2.6 | 7.7 ± 2.3 | 62.4 ± 15.4 | 7.2 ± 3.2 | 53.9 ± 11.1 |
| G121T | 5.6 ± 1.8 | 10.4 ± 3.5 | 41.2 ± 15.0 | 17.5 ± 6.8 | 16.4 ± 7.9 |
| G121V | 7.8 ± 3.7 | 8.8 ± 0.9 | 47.0 ± 16.4 | 4.4 ± 1.2 | 19.8 ± 9.4 |
| G121L | 14.6 ± 2.5 | 32.1 ± 4.8 | 49.7 ± 16.4 | 65.1 ± 6.8 | 16.1 ± 6.3 |
| G121I | 21.1 ± 4.8 | 47.7 ± 12.5 | 32.2 ± 10.8 | 78.9 ± 6.2 | 14.5 ± 4.6 |
| G121W | 30.0 ± 6.2 | 29.9 ± 4.0 | 15.4 ± 4.7 | 41.4 ± 15.3 | 10.2 ± 4.0 |
All of the values are presented as the mean ± SE from at least three measurements using at least two independent membrane preparations.
*
The dark activities are given as a percentage of transducin guanosine 5′-[γ-thio]triphosphate (GTP[γS]) activity measured in the dark normalized to the GTP[γS] uptake of the sample measured under continuous illumination.
†
The light activities of the mutant opsins in the presence of retinal analogues are percentages of the transducin activation by the opsin–retinal analogue complex in the light normalized to the transducin activation by the same opsin regenerated with retinal.