The chemiosmotic coupling hypothesis of oxidative phosphorylation proposes that adenosine triphosphate (ATP) is formed because:

(1) a proton gradient forms across the inner membrane

(2) high energy bonds are formed in mitochondrial proteins

(3) there is a change in the permeability of the inner mitochondrial membrane toward adenosine diphosphate (ADP)

(4) ADP is pumped out of the matrix into the intermembrane space