Adenosine triphosphate (ATP) is primarily known as the energy currency of the cell. It plays a critical role in intracellular energy transfer, providing the energy needed for various biological processes such as muscle contraction, nerve impulse propagation, and chemical synthesis. In cellular metabolism, ATP is generated during respiration and photosynthesis and is consumed in processes requiring energy input, including active transport across membranes and biosynthesis of proteins and nucleic acids.

In medicine, ATP is used in diagnostic procedures, particularly in nuclear stress tests, where it helps evaluate coronary artery disease by inducing vasodilation in heart vessels. It is also utilized in research settings to study cellular energetics, enzyme kinetics, and signal transduction pathways. Additionally, ATP is involved in extracellular signaling, where it acts as a neurotransmitter in purinergic signaling, influencing pain sensation, inflammation, and vascular regulation.

In biotechnology, ATP is used in assays to measure cell viability, as its presence indicates metabolically active cells. It is also a key component in luciferase-based systems for detecting microbial contamination in food and pharmaceuticals, leveraging the light-producing reaction when ATP interacts with luciferase enzymes.