What is ADP's role in the cell?

ADP or adenosine diphosphate plays several vital roles in the cell.

Its most important role is storing and releasing energy within an organism. ADP is one of the main building blocks for ATP, which is the source of cellular energy. Removal of the end phosphate group in ATP releases energy and converts the ATP to ADP, which is a low energy molecule. Adding a phosphate group to ADP uses up energy and recharges the ADP molecule back to ATP. The continuous recycling of between ADP and ATP ensures that the cell has a constant supply of energy-rich ATP to use for all metabolic pathways.

ADP also plays a role in muscle contraction and in initiating healing by activating blood platelets when a blood vessel is broken.