ATP is an in-vitro preparation of Adenosine Triphosphate, a form of energy used by the body.  Before energy can be utilized from carbohydrates, lipids or proteins, it must first be converted to ATP. Adenosine-5'-triphosphate (ATP) is a multifunctional nucleotide that is most important as a "molecular currency" of intracellular energy transfer. In this role, ATP transports chemical energy within cells for metabolism. It is produced as an energy source during the processes of photosynthesis and cellular respiration and consumed by many enzymes and a multitude of cellular processes including biosynthesis reactions, motility and cell division. In signal transduction pathways, ATP is used as as substrate by kinases that phophorylate proteins and lipids as well as by adenlylate cyclase, which uses ATP to produce the second messenger molecule cyclic AMP.