I am trying to find the concentration of CaN (PP2B) in dendritic spines, there is a computational model (doi:10.1073/pnas.0804672105) that uses the quantity of 1uM in the dendritic spine. I think this value is not correct since it was measured long time ago (Goto Brain Res. 1986 Nov 5;397(1):161-72) and was given as Hippocampus 1.45 -+ 0.39 (ug/mg of protein).

  • $\begingroup$ Why do you think the data is incorrect simply because it is old? The concentration can be high because the volume of the dendritic spine is very less. $\endgroup$ – WYSIWYG May 28 '19 at 11:58
  • $\begingroup$ This article says that CamKII concentration (different subunits) is ~60-140µM. Calcineurin should be in similar range, I guess. $\endgroup$ – WYSIWYG May 28 '19 at 12:11
  • $\begingroup$ I think that this measurement is incorrect for the spine because CaN localization is found in the spine neighborhood, not the whole neuron (that diluted the concentration). Being old is not a problem, sometimes it is gold, like Magee and Johnston (1995) VGCC measurements. A Lisman paper guesses that CaN concentration is maybe 20uM in the spine (CA1), but they don't provide the reference ... $\endgroup$ – Buzuzyma Jun 14 '19 at 11:46
  • $\begingroup$ Do you know how CaN and CamKII are correlated? I could not find any article on CaN concentrations but see my previous comment for CamKII concentration. You can at least make an informed guess for your computational model. I do believe, you would do some kind of sensitivity analysis with your model parameters; so a perfect value may not be essential. $\endgroup$ – WYSIWYG Jun 14 '19 at 11:58
  • $\begingroup$ How they are correlated? one is a phosphatase that presumably dephosphorylates (CaMKII), an experiment in 2015 is saying that is not the case but they didn't look into the dynamics with enough temporal resolution, as Chang/Yasuda 2017 did. For CaMKII there are several estimations of the spine concentration, which is really good. For CaN, the spine concentration is hard to trust. And there are values in literature from 1uM to 20uM. $\endgroup$ – Buzuzyma Jun 14 '19 at 12:06

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