Fig. 3: A unique movement of cytosolic domains and TMD during phosphorylation.

a Cytoplasmic domains of hSPCA1 in the CaE1 state. A, N, and P domains are colored cornflower blue, forest green, and peru, respectively. Conserved ¹⁸⁹TGE, ⁴⁸⁰KGA, and ³⁵⁰DKT motifs are colored hot pink, orange-red, and cyan, respectively. The dashed lines in the left inset show the distances from the Cα of Gly481 to the Cα of Lys351 and from the Cα of Glu191 to the Cα of Asp350. The right upper inset and right lower inset show the interaction surface between domains N and P, and that between domains A and P, respectively. The residues are shown as sticks. b Cytoplasmic domains of hSPCA1 in the CaE1-ATP state. AMP-PCP (purple ribbon), Mg²⁺ (dark red sphere), and the corresponding cryo-EM densities (black mesh, contoured at 16.8 σ) are shown. The dashed lines in the left inset show the distances from the Cα of Gly481 to the Cα of Lys351, and from the Cα of Glu191 to the Cα of Asp350. c Structural comparison of states CaE1 (tan), CaE1-ATP (light sky blue) and CaE1P-ADP (plum) of hSPCA1 by global alignment. d Structural comparison by P domain alignment (left) and TM3–TM4 alignment (right) of hSPCA1 (light sky blue) and SERCA1 (dark gray, PDB: 1T5S) in the CaE1-ATP state. The red arrow (right) shows the distance from the Cα of Pro82 in hSPCA1 to the Cα of Leu60 in SERCA1. e Structural comparison by global alignment (left) and TM3–TM4 alignment (right) of hSPCA1 (light sky blue) and NKA (dark gray, PDB: 7E21) in the substrate-bound E1-ATP state. f Structural comparison by P domain alignment (left) and TM3–TM4 alignment (right) of hSPCA1 (plum) and NKA (dark gray, PDB: 8D3U) in the substrate-bound E1P-ADP state. The red arrow (right) shows the distance from the Cα of Pro82 in hSPCA1 to the Cα of Gly89 in NKA.