Fig. 1: Phylogenetic and structural overview of the viral channelrhodopsins group.
From: Viral rhodopsins 1 are an unique family of light-gated cation channels
a Unrooted phylogenetic tree of the channelrhodopsin superfamily, including viral channelrhodopsin representatives. Scale bar indicates the average number of amino acid substitutions per site. CCR, cation-conducting channelrhodopsin, ACR, anion-conducting channelrhodopsin. OLPVR1 and VirChR1 proteins are additionally indicated in red. Rhodopsins were named according to the previous works18,101,102. b Crystal structure of OLPVR1 protein, viewed parallel to membrane (left), and from the extracellular side (right). All-trans retinal (ATR) is depicted with orange sticks. The hydrophobic membrane boundaries were calculated with the PPM server and are shown by gray lines103. c Structure alignment of OLPVR1 and CrChR2 (PDB ID: 6EID104) structures colored cyan and yellow, respectively. RMSD, root mean square deviation of atomic positions. d Individual TM helices are shown after the superimposition of the OLPVR1 and CrChR2 rhodopsins. e Structure alignment of OLPVR1 and bovine rhodopsin (PDB ID: 1U1943) structures colored cyan and purple, respectively. f Individual TM helices are shown after the superimposition of the OLPVR1 and bovine rhodopsin. g Alignments of functionally important residues of transmembrane helices 1, 2, 3, and 7 of representative proteins from channelrhodopsin subfamilies. Positively and negatively charged residues are highlighted blue and red; cysteine residues are highlighted green.
