Table 2. Diffusion constants for diffusible molecules in the model.
Molecule Name | Diffusion Constant (µm2/sec) |
Ca | 174.3 |
Calbindin | 9.3 |
CalbindinCa | 9.3 |
Da | 150 |
ATP | 74.7 |
AMP | 85.5 |
cAMP | 86.4 |
Cam | 11 |
CamCa2 | 11 |
CamCa4 | 11 |
CaMKIICamCa4 | 3.6 |
pCaMKIICamCa4 | 3.6 |
CaMKII | 3.6 |
pCaMKII | 3.6 |
PKAc | 8.1 |
DARPP32 | 10.6 |
DARPP32-PKAc | 10.6 |
pT34-DARPP32 | 10.6 |
pT75-DARPP32 | 10.6 |
pT75-DARPP32-PKAc | 10.6 |
Molecules not listed do not diffuse; thus, their diffusion constants are zero. To calculate diffusion coefficients as in [57] we used a cytosolic viscosity of 4.1 for small molecules and a cytosolic viscosity of ∼8.7 for proteins . These values yielded calcium gradients similar to those measured experimentally [59], and diffusion constants similar to those measured experimentally [50].