Fig. S1.

The lipid binding sites of CAR4. (A) The analysis of the anomalous difference density maps computed with data collected with crystals of CAR4 Ca²⁺ and Zn²⁺ at wavelength 1.7 (green) and 0.93 A (magenta) allows the unambiguous identification of the nature of the CAR4 metal centers, as Zn²⁺ and Ca²⁺ absorb radiation differentially at these wavelengths. The maps are contoured at 7 σ. (B) The polybasic binding site of CAR4 and three sections of the 2Fo-Fc simulated annealed omit map at the polybasic lipid binding site of CAR4 for the complex between CAR4 and PSF, the complex between CAR4 and POC, and the complex between CAR4, Zn, and POC.