| | Name | Initial Conc. (uM) | Volume (fL) | Buffered |
| 1 | AC1 | 0.02 | 1000 | No |
| | AC concentrations are tricky due to poor antibodies. I refer to an estimate from Jacobowitz, PhD Thesis, Mount Sinai School of Medicine around Pg 149 which estimates cyclase as 1/12600 of membrane protein. This gives a whole-cell conc of about 33 nM using assumptions of 2% of cell mass being membrane protein. Defer et al 2000 Am J Physiol Renal Physiol 279:F400-F416 in a good review put AC1 and AC8 (which has similar properties) as among the highly expressed form of brain cyclase. We therefore estimate its levels as a good fraction of the 33 nM, at 20 nM. |
| 2 | AC1-CaM | 0 | 1000 | No |
| | This state of AC1 is bound to Calmodulin and therefore activated. Gs stimulates it but betagamma inhibits. |
| 3 | AC1-Gs | 0 | 1000 | No |
| | This is the generic Gs-Stimulated state of AC1. Note that the enzyme is normally saturated, so all reactions involving AC1-Gs actually relate to the enzyme-substrate complex. |
| 4 | AC2 | 0.015 | 1000 | No |
| | AC concentrations are tricky due to poor antibodies. I refer to an estimate from Jacobowitz, PhD Thesis, Mount Sinai School of Medicine around Pg 149 which estimates cyclase as 1/12600 of membrane protein. This gives a whole-cell conc of about 33 nM using assumptions of 2% of cell mass being membrane protein. Defer et al 2000 Am J Physiol Renal Physiol 279:F400-F416 in a good review put AC2 among the highly expressed form of brain cyclase. We therefore estimate its levels as a good fraction of the 33 nM, at 15 nM. This actually adds up to a little more than 33, but it is well within error estimates. |
| 5 | AC2* | 0 | 1000 | No |
| | This is the phosphorylation-activated form of AC2. |
| 6 | AC2*-Gs | 0 | 1000 | No |
| | This is the form activated synergistically by phosphorylation as well as Gs binding. |
| 7 | AC2-Gs | 0 | 1000 | No |
| | This is the generic Gs-Stimulated form of AC2 |
| 8 | AMP | 10 | 0.0016667 | Yes |
| | AMP is a tightly regulated metabolite, so here we simply buffer it to its resting value. The value doesn't really matter to any of the calculations since it acts like a one-way sink. |
| 9 | ATP | 5000 | 1000 | Yes |
| | ATP is present in all cells between 2 and 10 mM. See Lehninger. |
| 10 | CaM.PDE1 | 0 | 1000 | No |
| | PDE1 is the 66 KDa form which binds CaM. Borisy et al J Neurosci 12(3):915-923 report a 6x stimulation with calcium. |
| 11 | cAMP-PDE | 0.45 | 1000 | No |
| | The levels of the PDE are not known at this time. However, enough kinetic info and info about steady-state levels of cAMP etc are around to make it possible to estimate this. |
| 12 | cAMP-PDE* | 0 | 1000 | No |
| | This form has about 2X activity as plain PDE. See Sette et al JBC 269:28 18271-18274 1994. |
| 13 | PDE1 | 2 | 1000 | No |
| | CaM-Dependent PDE. 66KDa Borisy et al J Neurosci 12(3):915-923 About 0.6% of membrane protein. so estimate 2 uM as conc in brain. Also see Conti et al Adv Sec Mess Phosphoprotein Res 1992 25:87-99 |
