| |
Name | Accession
Type | Initial
Conc.
(uM) | Volume
(fL) | Buffered | Sum Total Of |
| 1 | G-GDP | Network | 1 | 0 | No | - |
| | This is the G-alpha-beta-gamma trimer in association with GDP. From Pang and Sternweis JBC 265:30 18707-12 1990 we get concentration estimate of 1.6 uM to 0.8 uM. I use 1 uM which is well within this range. |
| 2 | mGluR | Network | 0.3 | 0 | No | - |
| | From Mahama and Linderman, Total # of receptors/cell = 1900 However, the density is likely to be very high at the synapse. Fay et al Biochem 30 5066-5075 1991 have a value of 60K receptors per cell for neutrophils which comes to 0.1 uM. Here we have a situation where trying to represent the synapse by a 10 micron cube gives awkward results. I will scale up to 0.3 uM since synaptic receptor density is likely to be higher, with the caveat that I should really be using a more geometrically realistic model. |
| 3 | Rec-Glu | Network | 0 | 0 | No | - |
| | Glu-Receptor complex. |
| 4 | Rec-Gq | Network | 0 | 0 | No | - |
| | Turns out that a large fraction of the the receptor binds to the G-protein even in the absence of ligand. This pool represents this step. Fraction of Rec-Gq is 44% of receptor, from Fay et al 1991 Biochem 30:5066-5075 Since this is not the same receptor, this value is a bit doubtful. Still, we adjust the rate consts in Rec-bind-Gq to match. |
| 5 | Rec-Glu-Gq | Network | 0 | 0 | No | - |
| | This is the ternary complex of receptor, ligand and G protein. |
| 6 | Blocked-rec-Gq | Network | 0 | 0 | No | - |
| | This represents the blocked state of the receptor when bound to a competitive antagonist. Note that this is in the Gq bound form. Simulations had shown that with the available rates, the blocking was minimal if only the unbound receptor could bind the antagonist. |
| 7 | G*GDP | Network | 0 | 0 | No | - |
| | This should correctly be called GDP.G_alpha. The name is preserved for backward compatibility reasons. |
| 8 | G*GTP | Network | 0 | 0 | No | - |
| | Activated G protein. Berstein et al indicate that about 20-40% of the total Gq alpha should bind GTP at steady stimulus. |
| 9 | BetaGamma | Network | 0 | 0 | No | - |
| | The betagamma subunits of Gq. This is an approximation to the possible combinations of betagamma subunits. Here they are all treated as a single pool. |
| 10 | mGluRAntag | Network | 0 | 0 | Yes | - |
| | I implement this as acting only on the Rec-Gq complex, based on a more complete model PLC_Gq48.g which showed that the binding to the receptor alone contributed only a small amount. |
| 11 | Glu | Network | 0 | 0 | Yes | - |
| | Varying the amount of (steady state) glu between .01 uM and up, the final amount of G*GTP complex does not change much. This means that the system should be reasonably robust wr to the amount of glu in the synaptic cleft. It would be nice to know how fast it is removed. Schoepp et al 1990 TIPS 11:508-515 give a range of Glu EC50 from rat brain in the range 120 to 1000 uM. Nicoletti 1986 PNAS 83:1931-1935 and Schoepp and Johnson 1989 J Neurochem 53:1865-1870 give an off time of at least 30 sec. |
and 
color.