Fig. 3: Identification of POPA lipid binding sites in the TREK1 channel structure.
From: Membrane phospholipids control gating of the mechanosensitive potassium leak channel TREK1
Cryo-EM density map of TREK1 solubilized in DDM detergent supplemented with POPA lipids (a), highlighting locations of bound POPA molecules (yellow). (b) Native mass spectrum of TREK1 dimer with POPA (left), and deconvoluted spectrum (right) showing multiple peaks corresponding to TREK1 dimer with up to eight bound POPA molecules (numbers above peaks indicate the number of bound POPA). Under more activating MS conditions (c), the number of bound POPA lipids is reduced to four, suggestive of two relatively higher affinity binding sites per subunit in the TREK1 dimer. d, e Zoomed-in views of two POPA binding sites identified in the cryo-EM density map where the POPA lipid interacts with the core of the TREK1 protein. Visualized lipid densities are derived from the final unsharpened C2 symmetrized TREK1 POPA map, visualized at a contour threshold of 0.0086.
