VATPaseen

VATPaseen, commonly referred to in English as the V-type ATPase or V-ATPase, is a multisubunit enzyme complex that hydrolyzes ATP to drive proton pumping across cellular membranes. By moving protons, it acidifies intracellular organelles such as lysosomes, endosomes, and the Golgi apparatus, and in some cell types can also extrude protons across the plasma membrane to acidify the extracellular space.

The enzyme consists of two main sectors. The V1 sector is peripheral and cytosolic, responsible for ATP hydrolysis, while the V0 sector is embedded in the membrane and forms the proton-conducting channel. The two sectors work together in a rotary mechanism: ATP hydrolysis causes rotation that translocates protons through V0, lowering the pH inside organelles and energizing secondary transport processes.

VATPaseen is widely distributed in eukaryotic cells. It localizes to lysosomes and endosomes, contributing to degradation and receptor trafficking, and to the Golgi apparatus, where it supports vesicle maturation. In specialized cells, such as osteoclasts and kidney intercalated cells, V-ATPase activity leads to extracellular acidification that is essential for bone resorption and urine acidification, respectively.

Regulation of VATPaseen involves reversible assembly of the V1 and V0 sectors and context-dependent expression of subunits. Activities are modulated by cellular energy status and interacting proteins, allowing dynamic control of organelle pH and transporter functions.

In medicine and research, V-ATPases are studied as targets for diseases involving organelle dysfunction, cancer, and bone disorders. Inhibitors like bafilomycin A1 are used as research tools to probe V-ATPase function.