Mitochondria have a crucial role in replenishing ATP, the molecule used to provide cellular energy. This is achieved by tightly coupling the movement of protons (H⁺) across the inner mitochondrial membrane to power the rotary action of ATP synthase in the final step of oxidative phosphorylation. Folds of the inner mitochondrial membrane called cristae provide a large, ion-impermeable surface area studded with respiratory enzymes including ATP synthase dimers. Structures of isolated ATP synthases have previously been determined, and by reconstituting into liposomes were observed to spontaneously form dimer rows that curve the liposomal membrane; however, the structure of ATP synthase has not been determined in its natural environment, which preserves the electrochemical proton gradient.

Now, using cryo-electron tomography (cryo-ET), Dietrich et al. have determined the structure of the mitochondrial ATP synthase within the unicellular alga Polytomella, which was flash-frozen under active growth conditions. The team observed an arrangement of parallel rows of ATP synthase dimers that twist around the cristae ridges with a left-handed helical geometry. The ATP synthase dimer rows define the shape of the cristae.

线粒体在补充 ATP 方面起着至关重要的作用，ATP 是用于提供细胞能量的分子。这是通过紧密耦合质子 （H⁺） 穿过线粒体内膜的运动来实现的，以在氧化磷酸化的最后一步中为 ATP 合酶的旋转作用提供动力。称为嵴的线粒体内膜的褶皱提供了一个大的、不透离子的表面积，上面布满了呼吸酶，包括 ATP 合酶二聚体。分离的 ATP 合酶的结构先前已经确定，并且通过重构到脂质体中观察到自发形成弯曲脂质体膜的二聚体行;然而，ATP 合酶的结构尚未在其自然环境中确定，它保留了电化学质子梯度。

现在，使用冷冻电子断层扫描 （cryo-ET），Dietrich 等人已经确定了单细胞藻类 Polytomella 内线粒体 ATP 合酶的结构，该藻类在活跃生长条件下被快速冷冻。该团队观察到平行的 ATP 合酶二聚体行的排列，这些二聚体以左旋螺旋几何形状围绕嵴脊扭曲。ATP 合酶二聚体行定义了嵴的形状。