ATP synthase dalton s) embedded in the inner membrane of mitochondria. Its function is to convert the energy of protons (H+) moving down their concentration gradient into the synthesis of ATP.TP synthase. Multimeric protein complex bound to inner mitochondrial membrane s, thylakoid membranes of chloroplasts, and the bacteria l plasma membrane that catalyzes synthesis of ATP during oxidative phosphorylation and photosynthesis; also called F0F1 complex. (Figure 16-28) ...