ATPases

ATPases are enzymes that hydrolyze adenosine triphosphate (ATP) to adenosine diphosphate (ADP) and inorganic phosphate, releasing energy that powers many cellular processes. They generate and maintain ion gradients, drive active transport, and regulate organelle function. ATPases are widespread in all domains of life and are key to energy metabolism, signal transduction, and cellular homeostasis.

Major families of ATPases include P-type, F-type, V-type, and ATP-binding cassette (ABC) transporters. Each family uses a distinct catalytic mechanism and substrate range, from ions and protons to diverse organic molecules.

P-type ATPases form a phosphorylated enzyme intermediate during transport of ions across membranes. They actively move cations such as Na+, K+, Ca2+, or H+. Classic examples include Na+/K+-ATPase and Ca2+-ATPase. F-type ATPases (F0F1-ATP synthases) function as rotary motors that couple proton or sodium gradients to ATP synthesis; they can also operate in reverse to hydrolyze ATP and pump ions. V-type ATPases pump protons into vacuoles and other organelles to acidify compartments and can also drive transport via ATP hydrolysis.

ABC transporters use nucleotide-binding domains to bind and hydrolyze ATP, powering the translocation of a broad range of substrates across membranes, including lipids, drugs, and metabolic products. In cellular energy metabolism and trafficking, F-type ATP synthase and V-type ATPases are central to energy conversion and organelle function, while P-type pumps maintain essential ion gradients. Defects in ATPases can contribute to various diseases, making them important targets in biomedical research.