Fig. 1
From: Improved methods for marking active neuron populations
In vitro characterization of CaMPARI2. a Primary (bottom) and tertiary (top) structures of CaMPARI2. Mutations relative to CaMPARI1_W391F-V398L are shown in red. Two orthogonal views of the same CaMPARI crystal structure (PDB ID 4OY4 [https://doi.org/10.2210/pdb4OY4/pdb] are shown. b Absorption (left) and fluorescence (right) excitation (full line) and emission (dotted line) spectra of CaMPARI2. Green and magenta spectra represent the green and red forms of CaMPARI; bright and dark lines represent the calcium-free and calcium-saturated states. c Photoconversion timecourse showing the red fluorescence of CaMPARI1 (black) and CaMPARI2 (red) as a function of exposure to 405 nm light. Left: photoconversion of purified CaMPARI protein in the presence (solid lines) or absence (dashed lines) of calcium. Right: photoconversion of primary rat hippocampal neurons with (solid lines) or without (dashed lines) 80 Hz stimulation. d Fold increase of the red-to-green ratio of CaMPARI variant-expressing neurons after 2 s of photoconversion during different electrical stimulation frequencies relative to no stimulation. Error bars are standard deviation, n = 3, asterisks denote values significantly differing from the corresponding CaMPARI1 value (p < 0.001, Dunnett’s multiple comparisons test)
