The enzyme that forms a channel in the inner membrane of mitochondria and phosphorylates ADP is ATP synthase.

Here's a breakdown:

* Channel Formation: ATP synthase has a channel through which protons (H+) flow from the intermembrane space to the mitochondrial matrix. This flow of protons is the driving force for ATP production.

* Phosphorylation of ADP: ATP synthase uses the energy released from the proton flow to catalyze the phosphorylation of ADP (adenosine diphosphate) into ATP (adenosine triphosphate). This process is called oxidative phosphorylation.

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