Figure 2. Architecture of the holocomplex.

(A and B) Cartoon representations of the holocomplex, colored as in Figure 1, and shown with semitransparent surfaces. Gray bars represent approximate boundaries of the hydrophobic core of the membrane. A Ca²⁺ion in the E ring is drawn as a purple sphere. The pore (semitransparent gray surface) is depicted as the minimal radial distance from its center to the nearest van der Waals protein contact. (C) Pore dimensions in structures of TcMCU-EMRE with and without MICU1-MICU2 (red and blue, respectively). A dashed line indicates the radius of a hydrated Ca²⁺ ion.

Figure 2—figure supplement 1. Comparison of the structures of TcMCU-EMRE with and without MICU1-MICU2.

Superposition of the structures of TcMCU-EMRE from the holocomplex (gold) and TcMCU-EMRE without MICU1-MICU2 (cyan) are shown in three orthogonal views. Ca²⁺ is depicted as a purple sphere. EMRE subunits are labeled 1 to 4. The RMSD for Cα atoms is 0.24 Å between the structures.