adenosine triphosphate

n. (ATP) A nucleotide synthesized in the mitochondria of all living cells which functions to store energy (C₁₀H₁₆N₅O₁₃P₃). Energy is released when adenosine triphosphate loses a phosphate group and is converted into adenosine diphosphate (ADP) in the Krebs cycle. ATP in neurons is sometimes converted by adenosine triphosphatase (ATPase) into cyclic adenosine monophosphate (AMP), which serves to help change the electric potential across the membrane of a cell during a nerve impulse.