Figure 4. Characterization of MICU1 and MICU2 interactions in both apo and Ca²⁺‐bound states.

• A
  GST‐MICU1_EF1^mut failed to pull down MICU2_WT in the absence of 2 mM Ca²⁺, whereas they displayed a strong interaction in the presence of 2 mM Ca²⁺.
• B
  GST‐MICU1_F383A & H385A failed to pull down MICU2_WT in the presence of Ca²⁺, whereas they displayed a strong interaction in the absence of 2 mM Ca²⁺.
• C
  GST‐MICU1_E242K failed to pull down MICU2_WT in the absence of Ca²⁺, whereas they displayed a strong interaction in the presence of 2 mM Ca²⁺.
• D
  GST‐MICU1_D231A partly pulled down MICU2_WT in the absence of Ca²⁺, whereas they displayed a strong interaction in the presence of 2 mM Ca²⁺.
• E
  GST‐MICU1_F383A failed to pull down MICU2_WT in the presence of Ca²⁺, whereas they displayed a strong interaction in the absence of 2 mM Ca²⁺.
• F
  GST‐MICU1_H385A exhibited a strong interaction with MICU2 in both the absence and presence of 2 mM Ca²⁺.
• G, H
  ITC analyses of MICU1 and MICU2 binding properties in the presence of 2 mM EGTA (G) and CaCl₂ (H).