3D-aligned tetrameric ion channels with universal residue labels for comparative structural analysis

Despite their large functional diversity and poor sequence similarity, tetrameric and pseudotetrameric potassium, sodium, calcium, and cyclic-nucleotide gated channels, as well as two-pore channels, transient receptor potential channels, and ionotropic glutamate receptor channels, share a common folding pattern of the transmembrane (TM) helices in the pore domain. In each subunit or repeat, two TM helices connected by a membrane-reentering …