Fig. 1: Calcium flux at high [Ca2+]e in selected CCRs.
From: Calcium-permeable channelrhodopsins for the photocontrol of calcium signalling
A CrChR2 crystal structure (PDB ID: 6EID, https://doi.org/10.2210/pdb6EID/pdb) with proposed ion permeation pathway (black arrow) and water densities after 10 ns MD simulation (grey mesh). Amino acids in stick representation have been previously associated with calcium permeation. Insets, right: H3 and H4) Helix 3 and Helix 4 with residues L132, D156 and F219 (Helix 6) and Central Gate) Central Gate formed by S63, E90 and N258. B Unrooted phylogenetic tree of chlorophyte CCRs. Coloured entries represent ChRs with calcium measurements in panels (C) and (D). Overview of depicted CCRs can be found in Supplementary Fig. 1. C Fura-2 imaging of calcium influx for different ChRs expressed in Fura-2-AM loaded ND7/23 cells probed with 10 s of 470 nm illumination (~0.08 mW/mm2, saturating conditions for C2-LC, indicated by blue bar) at 70 mM [CaCl2]e (mean ± SEM). D Quantified peak responses (as in panel C) after 10 s of illumination. Each dot represents one cell (mean ± SEM). Number of replicates: bReaCh-ES: n = 78; ChRmine: n = 37; C1C2: n = 45; CheRiff: n = 97; ReaChR: n = 89; ChRoME: n = 104; C1V1: n = 72; PsChR: n = 33; CrChR2: n = 104; TsChR: n = 49; C2-LC: n = 91; CoChR: n = 43. n = X biologically independent cells. EC extracellular, IC intracellular, R340/380 Fura-2 ratio, R0 Fura-2 ratio of first acquisition.
