What is ATP?
ATP is the primary source of cellular energy for all living things. It is found in every cell of the human body where it provides the energy to drive all of the biological reactions that allow cells to function and life to exist.
In addition to powering cellular processes, ATP is also an important signaling molecule, where cells release ATP to send messages to nearby cells.
ATP molecules store energy in the bonds between their phosphates; this energy is freed by a reaction that removes one phosphate group, leaving adenosine diphosphate (ADP). This process liberates about 30.6 kJ/mole of energy. ADP is then recycled (typically in the mitochondria) back into ATP via phosphorylation, the adding of a phosphate group. Each molecule of ATP in the human body is recycled 2,000-3,000 times in a single day.
Because ATP powers all biological processes, it also fuels exercise. In fact, the need for ATP increases up to 1,000-fold during exercise to meet the energy demands of the body. This is required to maintain the work rate, as ATP turnover can limit high-intensity performance.
ATP signaling was first detected between nerve cells and muscle tissue but is now known to work within and between a wide variety of cell types in the body, particularly in neurotransmission, muscle contraction, and cardiac function.
This is important as it highlights that not only ATP availability but also the timing and localization of ATP, can potentiate multiple physiological and metabolic actions.