Fig. 5: Structural comparison of hSPCA1 in three E2 states.

a Global alignment of the early E2P (color) and E2P (dark gray, PDB: 7YAM) states of hSPCA1. The red text shows the distance from the Cα of Leu96 in the early E2P state to the Cα of Leu96 in the E2P state. b Structural comparison of hSPCA1 TMD in the early E2P (color) and E2P (dark gray) states. c Comparison of TM4 and TM6, and the Ca²⁺-binding site between the early E2P state (orange-red) and the E2P state (dark gray) in hSPCA1. d Global alignment of the E2~P (color) and E2P (dark gray, PDB: 7YAM) states of hSPCA1. e Structural comparison of hSPCA1 cytoplasmic domains in the E2~P (color) and E2P (dark gray, PDB: 7YAM) states. The upper right panel shows the cryo-EM densities of AlF₄^–, Mg²⁺, Asp350, and Asp644 (black mesh, contoured at 10.0 σ). f The movement of the ¹⁸⁹TGE motif from the E2P state (dark gray, PDB: 7YAM) to the E2~P (color) state. The black dashed line show the distance between Cα of Glu191 in the E2P state and that in the E2~P state. g The interfaces between ¹⁸⁹TGE motif and P domain in the E2~P (color) and E2P states (dark gray, PDB: 7YAM). The EM densities of the ¹⁸⁹TGE motif and Thr352, Gly571, Asp572, and Asn647 in the E2~P state are shown (black mesh, contoured at 10.0 σ).