Table 2.
Parameters of the Spatiotemporal Model of Mouse Rod Phototransduction
| Parameter | Description | Value | Source | Reference/Method |
|---|---|---|---|---|
| kR | Rate of R* deactivation (s−1) | Genotype-dependent | Measured | Figure 1; also Gross and Burns (2010) |
| kE | Rate of G*-E* deactivation (s−1) | 5 | Measured | Figure 1; also Gross and Burns (2010) |
| νRE | Max rate of G*-E* activation per R* (s−1) | 300 | Literature | Leskov et al., 2000; Heck and Hofmann, 2001 |
| βidv | Rate of cGMP hydrolysis per G*-E* (s−1) | 43 | Literature | Gross et al. (2012) |
| βdark | Rate of spontaneous cGMP hydrolysis (s−1) | 4.1 | Literature | Gross et al. (2012) |
| DcG | Longitudinal diffusion coefficient of cGMP (μm2 s−1) | 40 | Literature | Gross et al. (2012) |
| fCa | Fraction of current carried by calcium | 0.12 | Literature | Gross et al. (2012) |
| αdark | Dark cGMP synthesis rate (μM s−1) | 16.7 | — | αmax/9; Gross et al. (2012) |
| Cadark | Dark adapted Ca2+ concentration (nM) | 320 | — | Set by αdark |
| cGdark | Dark adapted cGMP concentration (μM) | 4.1 | — | Set by αdark and βdark |
| BCa | Calcium buffer capacity | 50 | Fitted | ±15% of the values in Lagnado et al. (1992) and Nikonov et al. (1998) |
| ncyc | Hill coefficient for Ca2+ dependence of cGMP synthesis | 1.5 | Fitted | ±15% of the values in Makino et al. (2008) |
| Kcyc | K1/2 for Ca2+ dependence of cGMP synthesis (nM) | 80 | ||
| αmax | Max rate of cGMP synthesis (μM s−1) | 150 | ||
| Kex | K1/2 for NCKX activation (μM) | 1.1 | Fitted | ±15% of the values in Schnetkamp et al. (1991) |
| Jexsat | Maximum NCKX current (pA μm−1) | 0.21 | — | Set by Kex, Cadark, fCa, L |