Adenosine-5'-triphosphate (ATP) is an important molecule in vivo for energy storage and metabolism and is often called the "molecular unit of currency" of intracellular energy transfer. ATP is a coenzyme in multiple reactions as well as a substrate for multiple kinases where it helps to propagate a signal either inside or outside of the cell.

The three phosphates in ATP can be correlated with ADP and AMP. ATP consists of three phosphate groups attached in series to the 5’carbon location, whereas ADP contains two phosphate groups attached to the 5’ position, and AMP contains only one phosphate group attached at the 5’ position.